CI.5UA.  Bk yiiXSb-H 

TRINITY  COLLEGE 
LIBRARY 

DURHAM,  NORTH  CAROLINA 


Rec’d  .H.QV LI  A)9Q2 

ML 


MAP  OF  THE  MOON. 


SOUTH  POLE 


s 


Digitized  by  the  Internet  Archive 
in  2016  with  funding  from 
Duke  University  Libraries 


https://archive.org/details/hourswiththreein01  nobl 


HOURS  WITH  A 3-INCH  TELESCOPE 


PRINTED  BY 


5P0TTISW00DE  AND  CO.,  NEW -STREET  SQUARE 
LONDON 


\*\  VWO 


HOURS 


WITH  A THREE- INCH 


TELESCOPE 


BY 

CAPT.  WM.  NOBLE,  F.R.A.S,  F.R.M.S. 


HONORARY  ASSOCIATE  OF  THE  LIVERPOOL 
ASTRONOMICAL  SOCIETY 
ETC. 


n / go 

INDUSTRIAL  PUBLICATION  COMPANY 
15  DEY  STREET 
NEW  YORK 
1886 


i’g  a.  a 

H 7 5 3 H 


PREFACE. 


The  following  pages  are,  to  a large  extent,  a reprint  of  a 
series  of  papers  which,  at  the  request  of  my  friend  Mr. 
Proctor,  I wrote  for  the  columns  of  ‘ Knowledge,’  in  which 
they  originally  appeared.  The  work  in  its  collected  form 
simply  aims  at  being  a primer  of  the  Three-inch  Telescope, 
and  is  designed  to  instruct  the  very  beginner  in  the  use  of 
an  instrument  of  that  size,  mounted  on  a common  table 
stand  and  unprovided  wuth  any  means  of  finding  objects 
in  the  sky  by  means  of  their  co-ordinates.  The  reader  is 
further  supposed  to  know  no  more  of  the  constellations 
than  may  be  learned  from  ‘The  Stars  in  their  Seasons,’ 
wrhich  forms  one  of  the  series  of  the  ‘ Knowledge  Library.’ 
In  one  sense,  every  single  line  in  the  book  is  original  ; inas- 
much as  every  object  referred  to  was  actually  described  and 
drawn  by  myself,  at  the  eye  end  of  a telescope  of  three  inches 
aperture.  One  thing  I must  most  earnestly  disclaim,  and 
that  is  anything  in  the  shape  of  competition  or  rivalry  with 
any  existing  work  treating  of  telescopic  observation.  My 
highest  aspiration  will  be  fulfilled  if  this  little  book  should 
serve  as  an  introduction  to,  and  induce  the  amateur 


VI 


PREFACE. 


diligently  to  study,  a work  the  charm  of  whose  style  is  only 
equalled  by  the  scientific  value  of  its  contents  : I mean,  of 
course,  the  ‘ Celestial  Objects  for  Common  Telescopes  ’ of 
the  late  lamented  Prebendary  Webb.  I should  be  proud 
indeed  to  feel  that  my  unpretending  rudimentary  lessons 
had  been  the  means  of  introducing  the  student  to  that 
treasure-house  of  the  glories  and  beauties  of  the  heavens, 
and  should  appreciate  such  a result  as  the  highest  reward 
that  I could  receive  for  the  pains  and  trouble  I have  taken. 


CONTENTS 


CHAPTER  PAGE 

I.  THE  INSTRUMENT I 

II.  THE  SUN  . 8 

III.  THE  MOON 14 

IV.  OCCULTATIONS  OF  STARS  AND  PLANETS  BY  THE  MOON  44 

V.  MERCURY 50 

VI.  VENUS 53 

VII.  MARS 59 

VIII.  JUPITER 65 

IX.  SATURN 74 

X.  URANUS  AND  NEPTUNE 79 

XI.  DRAWING  THE  PLANETS 8l 

XII.  THE  FIXED  STARS  AND  NEBULAE 86 


MAP  OF  THE  MOON Frontispiece 


HOURS 

WITH 

A THREE-INCH  TELESCOPE. 


CHAPTER  I. 

THE  INSTRUMENT. 

This  little  book  is  written  to  furnish  the  very  beginner  in 
observational  astronomy  with  such  directions  as  shall  enable 
him  to  employ,  to  the  greatest  possible  advantage,  the  kind 
of  instrument  with  which  he  will,  in  all  probability,  at  first  pro- 
vide himself.  For,  be  it  noted  in  the  outset,  it  is  not  intended 
for  the  possessors  of  telescopes  of  considerable  aperture 
equatorially  mounted  or  furnished  with  elaborate  rackwork 
movements  in  altitude  and  azimuth.1  For  the  owners  of 
such  an  abundant  literature  is  already  in  existence  ; and 
they  have,  at  present,  such  admirable  works  as  Webb’s 
‘ Celestial  Objects  for  Common  Telescopes,’  Crossley,  Gled- 
hill,  and  Wilson’s  ‘ Handbook  of  Double  Stars,’  Chambers’s 
one-volume  edition  of  Smyth’s  ‘ Celestial  Cycle,’  <S;c.  I shall 
presuppose  nothing  on  the  part  of  the  reader,  then,  beyond 
an  ardent  desire  to  become  familiar  with  the  beauties  and 
glories  of  the  celestial  vault ; and  trust,  if  I can  secure  his 
attention,  to  put  him  fairly  in  the  way  of  gratifying  such  a 

1 These  terms  will  be  explained  as  I proceed. 


B 


2 


HOURS  WITH  A THREE-INCH  TELESCOPE. 


high  and  laudable  aspiration.  To  this  end  I shall  take 
as  my  text  the  maps  in  the  volume  entitled  ‘The  Stars 
in  their  Seasons,’  which  forms  one  of  the  ‘ Knowledge 
Library  ’ series.  I should  also  recommend  the  student  to 
possess  himself  of  the  smaller  Star  Atlas  by  Mr.  Proctor,  as 
well. 

As  it  is  of  the  first  importance  that  the  workman  should 
be  familiar  with  the  tools  he  has  to  use,  I propose  to  begin 
with  a description  of  the  telescope  itself,  which  I will  imagine 
to  be  a three-inch  achromatic  one,  of  about  forty-two  inches 
focal  length,  mounted  upon  an  ordinary  ‘ pillar-and-claw  ’ 
stand.  Such  an  instrument,  as  usually  sold,  is  shown  in  fig.  i, 
which,  however,  represents  it  as  furnished  with  a valuable 
little  subsidiary  contrivance  (to  be  immediately  described) 
that  the  observer  will  have  to  make  (or  to  get  made)  himself. 
And  here,  albeit  I am  earnestly  anxious  to  eliminate  the 
commercial  element  altogether  from  consideration,  I am 
compelled  to  caution  the  student  against  supposing  that  a 
first-class  three-inch  telescope  can  be  made  for  5/.,  or,  in 
fact,  for  any  sum  approaching  it.  The  object-glass  alone 
must  cost  the  maker  something  like  this  amount.  Hence, 
as  I propose  to  deal  with  and  describe  celestial  objects,  as 
seen  in  an  instrument  of  the  highest  class,  I give  this  pre- 
liminary warning,  lest  the  young  observer  should  spend  his 
money  on  a cheap  glass,  and  then  wonder  at  the  discrepancy 
between  the  delineations  of  stars  and  planets  in  the  following 
pages,  and  his  own  views  of  them.  There  is  a vast  amount 
of  rubbish  vended  in  the  'shape  of  (so-called)  cheap  tele- 
scopes, and  no  tyro  should  ever  purchase  such  a one  without 
its  previous  examination  and  testing  by  a skilled  expert. 
Makers  like  Cooke,  Dallmeyer,  Grubb,  and  Wray,  will  not 
imperil  their  great  and  deserved  reputation  by  selling  an 
inferior  object-glass  even  to  a total  stranger  : but  instru- 
ments of  unknown  opticians  require  the  most  rigid  trial 
before  they  can  be  safely  bought.  I shall  give,  further  on, 
a few  tests  by  which  the  student  himself  may  judge  some- 
what of  the  quality  of  an  instrument  he  may  propose  to 


THE  INSTRUMENT. 


3 


purchase.  It  is  time,  however,  to  turn  to  our  figure  below. 
Here  we  see  the  brass  tube  t,  into  one  end  of  which  screws 
the  cell  containing  the  object-glass  o.  Through  a tube 
projecting  from  the  brass  disc  which  covers  the  other  end 
of  t,  the  smaller  tube  s is  worked  in  and  out  by  the  milled 
head  f,  acting  on  a rack  and  pinion.  This  is  for  the  purpose 
of  focussing  the  telescope,  and  making  the  image  of  the 
object  observed  sharp  and  distinct.  Into  the  tube  s screws 
the  eye-piece  e,  consisting  of  two  lenses  mounted  in  a short 
piece  of  tubing.  Shortly,  the  action  of  the  instrument  is 


this.  The  object-glass  forms  in  its  focus  an  image  of  the 
object  to  which  it  is  directed,  and  the  eye-piece — which  is 
really  a microscope — magnifies  this  image  before  it  enters 
the  observer’s  eye.  So  much  for  the  telescope  itself.  It  is 
bolted,  as  will  be  seen,  by  two  screws  and  nuts,  to  a brass 
plate,  which  has  a vertical  motion  by  means  of  the  knuckle- 
joint  at  a,  at  the  top  of  the  stout  brass  pillar  a b,  and  a 
horizontal  one,  furnished  by  the  rotation  of  the  whole  of  this 
top,  fitting  inside  the  pillar.  Three  massive  feet  form  its 
support.  The  arm  b m,  shown  in  the  drawing,  forms  no 
part  of  the  ordinary  fitting  of  the  instrument ; it  constitutes 
the  subsidiary  contrivance  of  which  I spoke  above,  and  I 


4 


HOURS  WITH  A THREE-INCH  TELESCOPE. 


shall  explain  its  use  presently,  l in  the  figure  represents  a 
terrestrial,  or  four-lens  eye-piece,  which  shows  objects  erect, 
and  hence  is  used  for  land  purposes.  It  screws  in  at  the 
extremity  s,  just  as  e does.  The  ordinary  astronomical,  or 
so-called  ‘ Huyghenian  ’ eye-piece,  contains,  as  I have  pre- 
viously said,  only  two  lenses,  and  inverts,  or  turns  objects 
upside  down.  This,  however,  is  obviously  immaterial  in  a 
star  ; and  this  construction  of  the  eye-piece  enables  us  to 
obtain  high  magnifying  power  with  comparatively  small  loss 
of  light,  n is  another  astronomical  eye-piece,  and  p a dark 
glass  cap  or  shade,  screwing  on  to  every  eye-piece  for  the 
purpose  of  observing  the  sun.  The  student  is  earnestly 
warned  never  to  look  at  the  sun  through  a telescope  without 
first  covering  the  eye-piece  with  one  of  these  shades.  When, 
however,  I come  in  the  succeeding  chapter  to  speak  of  the 
sun,  I shall  describe  how  the  solar  details  may  be  telescopic- 
ally shown  without  looking  through  the  instrument  at  all. 
The  powers  usually  supplied  with  a telescope  of  the  size  I 
am  describing,  are  one  terrestrial  one,  magnifying,  perhaps, 
forty-five  diameters  ; and  three  astronomical  ones,  giving 
powers  of  something  like  50,100,  and  180.  If,  however,  its 
possessor  intends  to  devote  his  instrument  wholly  to  celestial 
observation,  I should  advise  him  to  replace  the  terrestrial 
eye-piece  by  two  Huyghenian  ones,  magnifying  twenty-five 
(for  comets,  nebulae,  and  clusters)  and  250  (for  close  double 
stars)  respectively.  For  night  use,  too,  a ‘ dew-cap  ’ will  be 
found  indispensable.  This  may  be  made  of  a tin  tube, 
bright  outside  and  blackened  within,  about  eight  inches  long, 
and  fitting  over  the  end  of  the  telescope  at  o.  This  prevents 
direct  radiation  from  the  object-glass  itself,  and  the  conse- 
quent deposition  of  dew  upon  it.  Never  wipe  your  object- 
glass  if  you  can  possibly  help  it.  Expose  it  to  the  heat  of  a 
fire  (not  too  near)  or  of  next  morning’s  sun  should  it  become 
heavily  dewed. 

A word  may  now  be  said  as  to  the  use  of  the  bar  B 11 
shown  in  our  sketch.  It  is  a fact  familiar  to  nearly  everyone 
who  has  ever  opened  an  Astronomical  Primer  (and,  at  any  rate, 


THE  INSTRUMENT. 


5 


to  be  established  by  a single  winter  night’s  observation  of 
the  sky  from  dusk  to  dawn),  that  the  stars  all  seem  to  de- 
scribe circles  round  a centre  in  the  northern  sky,  called  the 
pole,  very  close  to  which  is  situated  the  star  we  call  the  pole- 
star.  The  farther  we  go  from  this  centre,  the  larger  these 
circles  become,  up  to  a distance  of  90°  ; beyond  which  they 
begin  to  diminish  again.  Moreover,  the  point  round  which 
they  turn  is  in  this  country  something  over  50°  above  the 
northern  horizon  (depending  on  the  observer’s  latitude),  so 
that  they  are  all  described  obliquely  to  the  horizon.  Obvi- 
ously, were  the  apparent  axis  of  the  concave  celestial  vault 
vertical,  the  pole  would  be  overhead,  and  the  stars,  seeming  to 
describe  circles  parallel  to  the  horizon,  would  neither  rise  nor 
set.  In  this  imaginary  condition  of  things  (imaginary  in  Eng- 
land, but  it  really  exists  at  the  poles),  the  mounting  of  the  tele- 
scope shown  in  the  figure  above  would  enable  the  observer  to 
follow  a star  by  merely  turning  the  telescope  round  the  ver- 
tical axis  a b,  when  once  that  star  was  in  the  field  of  view  ; 
but  a moment’s  thought  will  show  that  a simple  movement 
round  a perpendicular  axis  will  by  no  means  accomplish  this 
when  the  star’s  path  is  described  round  an  inclined  one. 
The  vertical  movement  of  the  telescope,  I may  here  say,  is 
spoken  of  as  its  motion  in  altitude  ; its  horizontal  motion  as 
that  in  azimuth.  It  will  require  a little  more  attention  to 
see  that  if  we  so  tilted  the  axis  a b that  it  became  parallel  to 
(or  practically  coincided  with)  the  apparent  axis  of  the  sky, 
then  the  simple  motion  round  it  would  cause  the  telescope 
to  follow  any  star  to  which  it  was  directed,  from  its  rising  to 
its  setting.  A telescope  thus  placed  is  said  to  be  equato- 
rially  mounted.  Now  the  little  device  in  the  cut,  for  which, 
in  its  existing  form,  we  are  indebted  to  the  Earl  of  Crawford 
and  Balcarres,  is  intended  to  communicate  an  approximately 
equatorial  motion  to  the  object  end  of  a telescope  mounted 
as  above,  on  an  ordinary  altazimuth  stand.  It  takes  the 
form  of  a bar  b m,  extending  from  the  base  of  the  pillar  a b. 
In  it,  at  such  a distance  from  the  point  b,  vertically  under  a, 
that  the  angle  acb  shall  be  equal  to  the  latitude  of  the  place 


6 HOURS  WITH  A THREE-INCH  TELESCOPE. 

of  observation,  a hole  is  bored,  and  a thumb-screw  (shown 
at  c)  inserted  through  the  bar,  so  as  to  nip  a light  chain  or 
thin  wire  tight,  when  it  is  passed  through  the  hole.  The 
other  end  of  this  chain  is  fastened  anywhere  towards  the  end 
of  the  telescope  at  c',  and  sufficient  weight  is  put  on  to  the 
eye  end  of  the  telescope  to  keep  the  chain  or  wire  c c'  tight. 
Perhaps  I may  say  that  if  (as  is  very  common)  the  height 
from  a to  b is  1 1 inches,  the  hole  at  c may  be  8|  inches  from 
b.  This  will  give  a quasi-equatorial  movement  to  the  tele- 
scope for  London,  and  for  places  not  differing  much  from 
it  in  latitude.  The  use  of  this  contrivance  is  very  simple. 
The  bar  b m is  placed  due  north  and  south  (the  end  m of 
course  being  towards  the  south).  A star  is  got  into  the 
field,  and  the  chain  c c!  stretched  tight  and  made  fast.  Then 
the  observer  will  find  that  in  rotating  the  telescope  horizon- 
tally round  a,  the  end  o will  be  so  shackled  as  to  constrain 
it  to  follow  the  given  object. 

A few  miscellaneous  hints  may  conclude  what  I have  to 
say  on  the  telescope  itself.  First  the  reader  may  wish  to 
test  it  for  its  freedom  from  colour  and  aberration.  For 
the  first  let  him  turn  the  instrument  on  to  the  ‘ limb  ’ (or 
round  edge)  of  the  moon,  and  first  move  the  eye-piece  within 
the  focus  by  means  of  the  milled  head  f : then  a purple 
fringe  should  appear  on  the  lunar  limb.  On  moving  the 
eye-piece  outside  the  focus,  this  should  give  place  to  a green 
fringe  ; a telescope  that  exhibits  this  sequence  of  phenomena 


Fig.  2.  Fig.  3. 

is  achromatic.  For  spherical  aberration,  focus  the  telescope 
on  a tolerably  bright  star  with  the  whole  aperture,  and  then 


THE  INSTRUMENT. 


7 


put  a diaphragm  of,  say,  inch  aperture  over  the  object- 
glass,  and  see  if  the  star  remains  accurately  in  focus.  If  it 
does,  spherical  aberration  is  cured  too.  A bright  star  in  focus 
with  a power  of  150  should  present  the  appearance  of  fig.  2, 
and  by  no  means  that  of  fig.  3,  which  latter  indicates  a 
practically  worthless  object-glass.  Nor  should  any  illumi- 
nated haze  appear  about  bright  stars  or  planets.  Presuming 
that  the  instrument  acquired  by  the  student  whom  I am 
addressing  has  been  found  equal  to  these  tests,  he  may  pro- 
ceed to  put  it  to  practical  use.  The  first  object  to  which  it 
shall  be  directed  is  the  sun,  and  to  this  our  next  chapter 
shall  be  devoted. 


HOURS  WITH  A THREE-INCH  TELESCOPE. 


CHAPTER  II. 

THE  SUN. 

In  connection  with  the  observations  we  are  about  to 
attempt,  it  is  necessary  to  reiterate  and  emphasise  the  cau- 
tion given  on  p.  4.  On  no  account  then,  whatever,  must 
the  observer  attempt  to  look  at  the  sun  under  the  same 
instrumental  conditions  that  he  would  employ  in  viewing 
the  stars.  To  try  to  do  so  without  either  the  interposition 
of  a dark-coloured  eye-glass,  or  the  employment  of  a device 
to  be  immediately  explained,  is  almost  certain  to  involve 
permanent  blindness  altogether.  Sir  William  Herschel  lost 
an  eye  in  such  an  attempt;  an  attempt  against  which  I 
earnestly  warn  the  student.  As  a matter  of  practice,  how- 
ever, opticians  send  out  each  astronomical  or  Huyghenian 
eye-piece  with  a dark-glass  cap,  which  must  be  screwed  on 
whenever  the  sun  is  to  be  looked  at  directly  through  the 
telescope.  Should  the  purchaser  of  an  instrument  have  his 
choice  of  colour  in  these  eye-caps  I would  recommend  very 
dark  green  or  blue,  or  else  what  is  known  as  ‘ London 
smoke,’  as  the  most  agreeable  tints  for  use.  Red  glasses 
are  less  liable  to  crack  with  the  sun’s  heat,  but  they  are  by 
no  means  so  pleasant  to  look  through.  Whatever  colour, 
however,  the  observer  selects,  let  him  take  care  that  it  is 
dark  enough;  and  as  dark  glasses  are,  as  I have  hinted, 
liable  to  crack  with  the  sun’s  heat,  means  must  be  taken  to 
diminish  that  heat  as  much  as  possible.  This  will  involve, 
though,  one  of  two  things  : either  the  cutting  down  of  the 
aperture  of  the  instrument  to  two  inches,  or  even  less,  if 


THE  SUN. 


9 


the  observation  is  likely  to  be  a protracted  one ; or  the 
turning  away  the  object-glass  from  the  sun  at  short  inter- 
vals should  the  whole  of  the  object-glass  be  employed,  to 
give  the  eye-piece  time  to  cool.  There  is  a device  which, 
should  the  possessor  of  a telescope  choose  to  go  to  the  cost 
of  it,  enables  the  sun  to  be  viewed  for  an  almost  indefinite 
period  with  the  whole  aperture.  It  consists  simply  of  a 
perfectly  plane  plate  of  glass  placed  at  an  angle  of  45 ° 
with  the  axis  of  the  telescope,  so  as  to  reflect  the  image 
formed  by  the  objective  in  a direction  square  to  the  optical 
axis.  The  outside  of  this  plate  is  ground,  so  as  to  destroy 
any  secondary  reflection  ; and,  pretty  obviously,  a very  large 
proportion  indeed  both  of  the  sun’s  light  and  heat  passes 
through  it.  The  small  amount  which  is  reflected  passes 
into  an  ordinary  Huyghenian  eye-piece  (which  may  now  be 
covered  with  a lighter  eye-shade),  which  must  itself  be  ob- 
viously placed  at  right  angles  to  the  optical  axis  of  the  tele- 
scope. Or,  finally,  we  may  view  the  sun  without  looking 
through  our  telescope  at  all;  and,  for  getting  a general  idea  of 
solar  detail,  the  method  I am  about  to  describe  is  perhaps 
the  best  of  all.  Moreover,  it  enables  half-a-dozen  people  to 
view  the  solar  disc  at  once,  if  necessary.  In  this  way  of 
using  the  telescope  we  convert  it  into  a kind  of  solar  micro- 
scope or  magic-lantern,  and  throw  the  sun’s  image  on  to  a 
sheet  of  very  fine,  clean,  hot-pressed  cardboard,  which  we 
shift  to  and  from  the  eye-piece,  and  move  the  focussing 
tube  until  a sharp  and  distinct  image  of  the  sun  is  obtained. 
It  will  be  necessary  to  have  a large  sheet  of  pasteboard 
covered  with  black  paper,  through  a hole  in  the  middle  of 
which  the  eye-piece  comes,  in  order  to  shield  the  card  on 
which  the  image  is  projected  from  direct  sunlight.  The 
same  end  would  be  more  perfectly  attained  by  passing  the 
object  end  of  the  telescope  through  an  aperture  in  the 
shutter  of  a completely  darkened  room  ; but  this  is  rather 
too  elaborate  an  arrangement  for  the  ordinary  observer. 
Where  only  one  person  wishes  to  see  the  sun  at  a time, 
the  receiving  disc  may  be  fastened  at  the  bottom  of  a paste- 


IO  HOURS  WITH  A THREE-INCH  TELESCOPE. 


board  cone  fitting  over  the  eye  end  of  the  telescope,  and 
with  an  aperture  cut  in  the  side  to  look  through.  An 
arrangement  of  this  sort  is  illustrated  on  p.  136  of  the 
‘ Lessons  in  Elementary  Astronomy,’  by  the  editor  of 
‘ Knowledge,’  published  by  Messrs.  Longman.  Which- 
ever of  these  ways  we  select  to  view  the  sun  in,  we  shall  be 
struck  by  three  or  four  salient  features  of  his  surface.  The 
first  thing  we  shall  note  is  that  the  limb  or  edge  of  the  sun 
is  perceptibly  darker  than  the  middle  of  his  disc,  which 
gradually  shades  off  as  we  approach 
his  circular  outline.  The  effect  of  ro- 
tundity which  this  gives  to  his  image 
is  very  striking.  A little  considera- 
tion will  show  that  this  must  be  the 
effect  of  an  atmosphere  surrounding 
what  is  technically  called  the  photo- 
sphere, or  light-radiating  surface  of 
the  sun.  The  next  thing  that  will 
arrest  our  attention — perhaps  just  now  1 the  first — will  be 
the  dark  spots  which  diversify  the  sun’s  face. 

The  above  figure  may  serve  as  an  illustration  of  an  in- 
dividual single  spot,  and  was  drawn  with  a power  of  80,  on 
Wednesday,  September  12,  1883,  at  11  25  a.m.  It  will  be 
seen  to  consist  of  two  well-distinguished  parts,  a dark  in- 
terior one,  known  technically  as  the  umbra  (three  of  these 
umbrae  at  least  will  be  observed  to  be  included  in  the  pen- 
umbra in  the  sketch  above),  surrounded  by  a lighter  fringing 
which  is  called  the  penumbra.  By  the  use  of  a peculiarly 
constructed  eye-piece,  and  a telescope  of  considerable  aper- 
ture, the  late  Mr.  Dawes  discovered  black  spots  within  all 
large  umbrae,  and  even  some  small  ones.  If  the  observer 
knows  exactly  what  to  look  for,  he  may  sometimes  pick 
these  up  even  with  a three-inch  telescope.  It  will,  however, 
be  necessary  to  cover  the  diaphragm  in  the  eye-piece  with  a 
circular  disc  of  glazed  visiting  card  (with  the  glazed  side 

1 This  was  written  in  1S85,  when  a sun  spot  maximum  was 
approaching. 


Fig.  4. — Spot  on  Sun, 
Sept.  12,  1883,  11.25  a.m. 


THE  SUN. 


1 1 

towards  the  field  glass),  centrally  perforated  with  a minute 
hole  made  with  a fine  red-hot  needle.  The  telescope  is 
moved  until  the  spot  occupies  this  exceedingly  circum- 
scribed field  ; and  thus  cut  off  from  the  surrounding  glare, 
the  nucleus  may  often  be  detected.  I have  so  far  spoken 
as  though  spots  were  isolated,  but  they  perhaps  most  fre- 
quently appear  in  groups,  involving  the  most  enormous 
areas  on  the  sun’s  surface,  of  the  disturbances  of  which 
they  are  the  outward  and  visible  sign. 

Our  next  figure  represents  a group  of  spots  visible 
on  the  sun  at  9.50  a.m.  on  June  30th  of  the  same  year, 
and  was  drawn  (as  in  the  case  of  every  other  figure 
which  appears  in  these 
pages)  at  the  telescope. 

As  a reflecting  eye-piece 
was  used  in  this  particular 
case,  though,  everything  is 
turned  right  for  left  in  the 
engraving.  It  will  be  noted 
how  the  curves  of  the 
penumbrse  connected  the 
umbrae.  Micrometrical 
measurement  made  imme- 
diately after  our  sketch 
gave  the  superficial  area 
of  the  left-hand  group  as  762,940,200  square  miles,  and 
that  of  the  right-hand  one  1,074,370,000  square  miles,  or 
in  all  1,837,310,200  square  miles  of  the  sun’s  surface,  as 
involved  in  this  stupendous  disturbance  alone  ! It  could 
be  seen  with  the  naked  eye  when  defended  by  a darkened 
or  smoked  glass.  There  were  other  spots  on  the  sun’s  disc 
at  the  time.  Careful  study  of  the  spots  under  the  most 
favourable  definition  will  reveal  certain  striking  features. 
The  umbrre,  under  ordinary  circumstances,  seem  to  be 
black;  but  the  student  who  has  the  opportunity  of  watch- 
ing a partial  solar  eclipse,  or  a transit  of  Mercury,  will  at 
once  be  struck  with  the  extreme  blackness  of  the  moon’s 


Fig.  5.— Group  of  Spo*s,  June  30,  1883, 
9 50  a m.  (visible  to  the  naked  eye). 


12  HOURS  WITH  A THREE-INCH  TELESCOPE. 


limb  or  of  the  planet,  as  contrasted  with  the  (now,  by  con- 
trast) brown  hue  of  the  spots.  A distinctly  brown  and  even 
orange  tinge  may  often  be  seen  in  the  images  of  spots  pro- 
jected on  to  a sheet  of  cardboard  in  the  manner  described 
above.  Attentive  study  of  the  penumbra  will  reveal  a kind 
of  fimbriated  or  fringed  appearance  in  it;  and  it  will  be 
further  noticed  to  be  darkest  at  its  outer  edge,  and  seem- 
ingly to  get  lighter  as  it 
approaches  the  umbra. 
Returning  now  to  the 
limb  or  edge  of  the  sun 
— which,  as  I have  pre- 
viously said,  will  be  per- 
ceived to  be  notably 
darker  than  the  centre 
of  his  disc  — we  shall 
find  the  shading  diver- 
sified by  curious  and 
often  rather  compli- 
cated streaks  of  light. 
These  are  called  ‘ fa- 
culte,’  and  are  most 
numerous  and  con- 
spicuous about  spots 
which  are  close  to  the 
limb,  or  where  such 
spots  are  about  to 
break  out.  I have 
sometimes  traced  fa- 
culae  for  some  con- 
siderable distance  on  to  the  brighter  part  of  the  sun's  disc  ; 
but,  as  a rule,  they  are  only  seen  near  the  limb.  The 
accompanying  sketch  represents  a group  of  faculm  which 
was  visible  on  the  morning  of  August  25th,  1SS3,  at  9 h. 
40  min. 

It  was  drawn  on  the  paper  on  to  which  the  image  of  the 
sun  was  projected,  in  the  manner  previously  described. 


Fig.  6. — Faculae  on  Sun’s  limb,  Aug.  25,  1883, 
9.40  a.m. 


THE  SUN. 


13 


The  fourth  piece  of  solar  detail  of  which  I need  here  speak 
is  the  mottling  or  graining  of  his  surface.  This  is  best 
caught  by  shifting  the  telescope  a little,  so  as  to  make  the 
sun’s  image  move  about  in  the  field.  If  this  be  done,  the 
eye  will  soon  receive  the  impression  of  a roughness  or  grain 
upon  the  sun’s  face,  akin  to  that  of  a piece  of  magnified 
loaf-sugar.  In  large  instruments  this  is  seen  under  the  best 
definition  to  consist  of  markings  which  have,  not  unaptly, 
been  compared  to  rice  grains,  but  its  resolution  into  these 
appearances  is  wholly  beyond  our  instrumental  power. 

Such  are  the  leading  features  observable  on  the  surface 
of  the  sun  with  the  means  at  our  disposal.  I may  say,  how- 
ever, with  reference  to  them,  that  I am  not  writing  a helio- 
graphical  treatise  ; and  hence,  for  their  interpretation,  must 
refer  the  reader  to  ‘ The  Sun,’  by  Mr.  R.  A.  Proctor,  or  to 
the  volume  of  the  ‘ International  Scientific  Series  ’ bearing 
the  same  title,  by  Professor  Young.  I have  simply  essayed — 
not,  I trust,  wholly  without  success — to  indicate  what  maybe 
seen  upon  the  sun  in  a three-inch  telescope.  By  the  aid  of 
Browning’s  star  spectroscope,  with  a very  narrow  slit,  the 
spectra  of  prominences  (those  huge  uprushes  of  hydrogen 
gas  known  as  the  ‘ red  flames  ’ which  are  seen  during  a 
total  solar  eclipse)  may  often  be  detected  on  the  sun’s  limb, 
even  in  a telescope  of  the  size  of  that  whose  use  is  pre- 
supposed ; but  the  mention  of  the  fact  must  suffice  here. 


14  HOURS  WITH  A THREE-INCH  TEI.ESCOFE. 


CHAPTER  III. 

THE  MOON. 

Of  the  moon  I shall  treat  somewhat  more  in  detail,  as, 
probably,  one  of  the  first  objects  to  which  the  incipient 
possessor  of  a telescope  will  be  likely  to  direct  his  instru- 
ment and  attention.  But  I am  not  going  to  write  here  a com- 
plete treatise  on  selenography.  Those  of  my  readers  whom 
I may  succeed  in  interesting  sufficiently  in  this  subject  will, 
doubtless,  proceed  to  the  section  devoted  to  it  in  Webb’s 
admirable  work,  ‘Celestial  Objects  for  Common  Telescopes,’ 
and  to  that  even  more  elaborate  ^one,  ‘The  Moon,’  by  Mr. 
E.  Neison,  which  may  be  fairly  regarded  as  a kind  of  lunar 
encyclopaedia.  What  I propose  to  do  in  these  pages  is  to  point 
out  to  the  possessor  of  a three-inch  telescope  exactly  what 
it  may  be  expected  to  show  him  in  the  shape  of  lunar  scenery, 
and  of  the  general  physical  conformation  of  our  satellite. 
To  this  end  I present,  in  the  frontispiece,  a map  of  the  moon, 
founded  on  the  excellent  one  by  Mr.  Webb,  and  which  also 
appears  in  the  volume  on  ‘The  Moon,’  by  Mr.  Proctor.  I 
have  purposely  retained  the  lettering  and  numberingadopted 
by  Mr.  Webb  to  facilitate  reference,  and  propose  to  describe 
and  draw  a selection  of  the  objects  thus  indicated,  with  the 
end  of  familiarising  the  student  with  the  principal  features 
of  the  surface  of  our  satellite.  Some  of  the  chief  of  these 
I have  drawn  at  the  telescope,  in  order  that  the  young 
observer  may  know  precisely  what  to  look  for  : and  I shall 
in  all  cases  give  the  exact  age  of  the  moon  and  the  power 
employed,  in  order  that  the  sketches  so  made  may  be  directly 


THE  MOON. 


15 


comparable  with  the  moon  herself.  The  map  almost  explains 
itself.  It  gives  an  inverted  image  of  the  moon  as  it  would 
appear  in  a telescope  with  an  ordinary  Huyghenian  eye- 
piece of  low  power.  The  curved  lines  represent  the  lines  of 
lunar  longitude,  the  moon  being  supposed  to  be  in  what  is 
called  her  condition  of  ‘ Mean  Libration.’  The  meaning  of 
this  phrase  (which  is,  however,  not  very  material  for  our 
present  purpose)  will  be  found  thoroughly  explained  in  the 
work  on  ‘ The  Moon,’  by  the  editor  of  ‘ Knowledge,’  to  which 
I have  referred  above.  One  immediate  use  to  which  we 
may  put  these  lines  is  this.  The  curve  separating  the  il- 
luminated part  of  the  moon’s  disc  from  the  dark  part  (tech- 
nically called  the  ‘terminator’)  creeps  over  her  face  at  the 
rate  of  120  n'  267"  per  diem.  Hence,  when  she  is  one  day 
old,  the  central  part  of  this  arc  will  be  in  lunar  longitude 
770  48'  33'3"  east  of  her  centre  ; at  two  days  old,  at  longitude 
65°  37'  6 -6"  east ; and  so  on  until  she  is  778  days  old,  when 
she  will  be‘  dichotomised,’  or  exactly  half  light  and  half  dark. 
So  far  the  bright  crescent  is  concave  towards  the  east.  After- 
wards, when  the  moon  has  entered  her  ‘ first  quarter,’  the 
‘terminator’  becomes  convex  towards  the  east,  and  continues 
to  increase  in  convexity  until  full  moon,  when  it  merges  in 
the  moon’s  general  circular  outline.  Pretty  obviously  these 
phenomena  recur  in  reverse  order  between  the  time  of  full 
moon  and  that  of  her  becoming  ‘new’  again.  Suppose, 
now,  that  the  student  wishes  to  know  what  formations  are 
near  to  the  boundary'  of  light  and  darkness  when  the  moon 
is  5 days  old.  5 x 120  1 1'  267”  = 6o°  57'  13-5",  the  longi- 
tude of  the  terminator  from  the  west  limb.  Taking  this 
from  90°,  we  find  290  2'  46-5''  as  its  longitude  from  the 
moon’s  centre  ; and  now,  looking  at  the  map,  we  see  that 
while  the  craters  and  ring  plains  374,  371,  372,  323,  57,  48, 
37,  &c.,  will  all  be  illuminated  (albeit  very  obliquely),  the 
sun  will  not  yet  have  risen  on  367,  321,  320,  319,  318,  47, 
and  50,  and  only  partially  on  54.  In  like  manner,  the 
position  of  the  terminator  at  any  other  age  of  the  moon 
may  be  determined. 


1 6 HOURS  WITH  A THREE-INCH  TELESCOPE. 

In  fact,  my  chief  object  in  introducing  these  lines  of 
longitude  at  all  is  to  supply  the  beginner  with  the  means  of 
ascertaining  with  sufficient  accuracy  when  any  given  forma- 
tion is  most  favourably  placed  for  observation,  and  inci- 
dentally of  identifying  it.  When  once  he  is  familiar  with 
the  leading  features  of  the  lunar  surface,  he  will  easily  be 
able  to  determine  for  himself  the  times  at  which  they  can 
be  most  advantageously  examined.  If  we  reflect  for  a little, 
it  will  be  seen  that  this  must  evidently  be  when  the  object 
under  examination  is  most  obliquely  illuminated — in  other 
words,  when  it  is  tolerably  near  to  the  boundary  line  between 
light  and  darkness.  Suppose  that  we  had  to  determine  the 
shape  of  a white  basin  at  a distance  of  a couple  of  miles, 
with  a pocket  telescope,  at  night,  and  had  our  choice  as  to 
the  method  of  illuminating  it.  Obviously  we  should  not  cast 
the  light  of  a lantern  directly  into  it — or  we  should  perceive 
nothing  but  a circular  white  patch  in  the  telescope.  We 
should  light  it  from  the  side  ; the  shadows  which  it  would  in 
consequence  cast  revealing  its  contour  distinctly.  Now,  at 
full  moon  the  sun  is  (for  our  present  purpose)  shining  verti- 
cally on  to  our  satellite,  which,  consequently,  presents 
nothing  but  a mottled,  spotted,  and  shaded  surface,  the 
most  conspicuous  features  being  certain  dark  patches, 
erroneously  named  ‘ seas,’  and  a radiating  series  of  streaks 
issuing  from  a crater  (hereafter  to  be  described),  calledTycho, 
situated,  in  an  inverting  telescope,  towards  the  top  of  the  moon. 
People  with  keen  vision  can  detect  this  system  of  streaks 
with  the  naked  eye  ; when  so  seen,  though,  they,  of  course, 
seem  to  radiate  from  the  southern  part,  or  bottom , of  the 
moon.  With  these  preliminary  remarks,  I may  proceed  to 
furnish  a key  to  the  map  forming  the  frontispiece.  I merely 
give  the  names  of  the  various  formations  here,  reserving  any 
description  of  them  individually  until  I come  to  treat  of  their 
aspect  in  the  telescope.  Beginning,  then,  with  the  chief 
dark  markings  or  patches  : — 

A,  Sea  of  Conflicts.  B,  Humboldt's  Sea.  C,  Sea  of  Cold. 
D,  Lake  of  Death.  E,  Lake  of  Dreams.  F,  the  Marsh  of  a Dream. 


THE  MOON. 


17 


G,  the  Sea  of  Tranquillity.  H,  the  Sea  of  Serenity.  I,  the  Marsh  of 
Clouds.  K,  the  Marsh  of  Corruption.  L,  Sea  of  Vapour.  M,  Middle 
Bay.  N,  Bay  of  Heat.  O,  Sea  of  Showers.  P,  Bay  of  Rainbows. 
Q,  Ocean  of  Storms.  R,  Bay  of  Dew.  S,  Sea  of  Clouds.  T,  Sea  of 
Moisture.  V,  Sea  of  Nectar.  X,  Sea  of  Fertility.  Y,  Smyth’s  Sea. 
Z,  the  South  Sea. 

Ring-Plains,  Craters,  .Mountain  Ranges,  &c. 


1.  Promontorium 

Agarum 

2.  Alhazen 

3.  Eimmart 

4.  Picard 

5.  Condorcet 

6.  Auzout 

7.  Firmicus 

8.  Apollonius 

9.  Napier 

10.  Schubert 

11.  Hansen 

12.  Cleomedes 

13.  Tralles 

14.  Oriani 

15.  Plutarch 

16.  Seneca 

17.  Hahn 

18.  Berosus 

19.  Burckhardt 

20.  Geminus 

21.  Bernouilli 

22.  Gauss 

23.  Messala 

24.  Schumacher 

25.  Struve 

26.  Mercury 

27.  Endymion 

28.  Atlas 

29.  Hercules 

30.  Oersted 

31.  Cepheus 

32.  Franklin 

33.  Berzelius 


34.  Hooke 

35.  Strabo 
6.  Thales 

37.  Gartner 

38.  Democritus 

39.  Arnold 

40.  Christn.  Mayer 

41.  Meton 

42.  Euctemon 

43.  Scoresby 

44.  Gioja 

45.  Barrow 

46.  Archytas 

47.  Plana 

48.  Mason 

49.  Baily 

50.  Burg 

51.  Mount  Taurus 

52.  Romer 

53.  Le  Monnier 

54.  Posidonius 
53.  Littrow 

56.  Maraldi 

57.  Vitruvius 

58.  Mount  Argaeus 

59.  Macrobius 

60.  Proclus 

61.  Pliny 

62.  Ross 

63.  Arago 

64.  Ritter 

65.  Sabine 

66.  Jansen 

67.  Maskelyne 


68.  Mount  Hsemus 

69.  Promontorium 

Acherusia 

70.  Menelaus 

71.  Sulpicius  Gallus 

72.  Taquet 

73.  Bessel 

74.  Linne 

75.  Mount  Caucasus 

76.  Calippus 

77.  Eudoxus 

78.  Aristotle 

79.  Egede 

80.  Alps 

81.  Cassini 

82.  Theaetetus 

83.  Aristillus 

84.  Autolycus 

85.  Apennines 

86.  Aratus 

87.  Mount  Hadley 

88.  Conon 

89.  Mount  Bradley 

90.  Mount 

Huyghens 

91.  Marco  Polo 

92.  Mount  Wolf 
93-  Hyginus 

94.  Triesnecker 

95.  Manilius 

96.  Julius  Caesar 

97.  Sosigenes 
9S.  Boscovich 
99.  Dionysius 

C 


1 8 HOURS  WITH  A THREE-INCH  TELESCOPE. 


100.  Ariadseus 

101.  Silberschlag 

102.  Agrippa 

103.  Godin 

104.  Rhseticus 

105.  Sommering 

106.  Schroter 

107.  Bope 

108.  Pallas 

109.  Ukert 

no.  Eratosthenes 
in.  Stadius 

1 1 2.  Copernicus 

1 13.  Gambart 

1 1 4.  Reinhold 

115.  Carpathian  Mts. 

1 16.  Gay  Lussac 

1 1 7.  Tobias  Mayer 

1 1 8.  Milichius 

1 19.  Hortensius 

120.  Archimedes 

1 21.  Timocharis 

122.  Lambert 

123.  La  Hire 

124.  Pytheas 

125.  Euler 

1 26.  Diophantus 

127.  Delisle 

128.  Carlini 

129.  Helicon 

130.  Kirch 

131.  Pico 

132.  Plato 

133.  Harpalus 

134.  La  Place 

135.  Heraclides 

136.  Maupertuis 

137.  Condamine 

138.  Bianchini 

139.  Sharp 

140.  Mairan 

141.  Louville 

142.  Bouguer 


143.  Encke 

144.  Kepler 

145.  Bessarion 

146.  Reiner 

147.  Marius 

148.  Aristarchus 

149.  Herodotus 

1 50.  Wollaston 

1 5 1.  Lichtenberg 

152.  Harding 

153.  Lohrmann 

154.  Hevelius 

155.  Cavalerius 

156.  Galileo 

157.  Cardan 

158.  Krafft 

159.  Olben 

160.  Vasco  de  Gama 

161.  Hercynian  Mts. 

162.  Seleucus 

163.  Briggs 

164.  Ulugh  Beigh 

165.  Lavoisier 

166.  Gerard 

167.  Repsold 

168.  Anaxagoras 

169.  Epigenes 

170.  Timseus 

1 7 1.  Fontenelle 

172.  Philolaus 

173.  Anaximenes 

174.  Anaximander 

175.  Horrebow 

176.  Pythagoras 

1 77.  GEnopides 

178.  Xenophanes 

1 79.  Cleostratus 

180.  Tycho 

1 8 1.  Pictet 

182.  Street 

183.  Sasserides 

184.  Hell 

185.  Gauricus 


186.  Pitatus 

187.  Hesiod 

188.  Wurzelbauer 

189.  Cichus 

190.  Heinsius 

1 91.  Wilhelm  I. 

192.  Longomontanus 

193.  Clavius 

194.  Deluc 

195.  Maginus 

196.  Saussure 

197.  Orontius 

198.  Nasir-ed-din 

199.  Lexell 

200.  Walter 

201.  Regiomontanus 

202.  Purbach 

203.  Thebit 

204.  Arzachel 

205.  Alpetragius 

206.  Promontorium 

/Enarium 

207.  Alphonsus 

208.  Ptolemy 

209.  Davy 

210.  Lalande 

21 1.  Mosting 

212.  Herschel 

213.  Bullialdus 

214.  Kies 

215.  Guericke 

216.  Lubiniezky 

217.  Parry 

218.  Bonpland 

219.  Fra  Mauro 

220.  Riphrean  Mts. 

221.  Euclid 

222.  Landsberg 

223.  Flamsteed 

224.  Letronne 

225.  Hippalus 

226.  Campanus 

227.  Mercator 


THE  MOON. 


19 


228.  Ramsden 

229.  Vitello 

230.  Doppelmeyer 

231.  Mersenne 

232.  Gassendi 

233.  Agatharchides 

234.  Schiller 

235.  Bayer 

236.  Rost 

237.  Hainzel 

238.  Capuanus 

239.  Schickard 

240.  Drebbel 

241.  Lehmann 

242.  Phocylides 

243.  Wargentin 

244.  Inghirami 

245.  Bailly 

246.  Dorfel  Mts. 

247.  Hausen 

248.  Segner 

249.  Weigel 

250.  Zuchius 

251.  Bettinus 

252.  Kircher 

253.  Wilson 

254.  Casatus 

255.  Klaproth 

256.  Newton 

257.  Cabeus 

258.  Malapert 

259.  Leibnitz  Mts. 

260.  Blancanus 

261.  Schemer 

262.  Moretus 

263.  Short 

264.  Cysatus 

265.  Gruembergor 

266.  Billy 

267.  Hansteen 

268.  Zupus 

269.  Fontana 

270.  Sirsalis 


271.  Damoiseau 

272.  Grimaldi 

273.  Riccioli 

274.  Cordilleras 

275.  D’Alembert 

Mts. 

276.  Rook  Mts. 

277.  Rocca 

278.  Criiger 

279.  Bergius 

280.  Eichstadt 

281.  Lagrange 

282.  Piazzi 

283.  Bouvard 

284.  Vieta 

285.  Fourier 
2S6.  Cavendish 

287.  Reaumur 

288.  Hipparchus 

289.  Albategnius 

290.  Parrot 

291.  Airy 

292.  La  Caille 

293.  Playfair 

294.  Apianus 

295.  Werner 

296.  Aliacensis 

297.  Theon  sen. 

298.  Theon  jun. 

299.  Taylor 

300.  Alfraganus 

301.  Delambre 

302.  Kant 

303.  Dollond 

304.  Des  Cartes 

305.  Abulfeda 

306.  Almamon 

307.  Tacitus 

308.  Geber 

309.  Azophi 

310.  Abenezra 

31 1.  Pontanus 

312.  Sacrobosco 


313.  Pons 

314.  Fermat 

315.  Altai  Mts. 

316.  Polybius 

317.  Plypatia 

318.  Torricelli 

319.  Theophilus 

320.  Cyrillus 

321.  Catherine 

322.  Beaumont 

323.  Isidore 

324.  Capella 

325.  Censorinus 

326.  Taruntius 

327.  Messier 

328.  Goclenius 

329.  Biot 

330.  Guttemberg 

331.  Pyrenees 

332.  Bohnenberger 

333.  Colombo 

334.  Magelhaens 

335.  Cook 

336.  Santbech 

337.  Borda 

338.  Langrenus 

339.  Vendelinus 

340.  Petavius 

341.  Palitzsch 

342.  Hase 

343.  Snell 

344.  Stevinus 

345.  Furner 

346.  Maclaurin 

347.  Kastner 

348.  La  Perouse 

349.  Ansgarius 

350.  Behaim 

351.  Hecatteus 

352.  Wilhelm  Hum- 

boldt 

353.  Legendre 

354.  Stofler 

c 2 


20  HOURS  WITH  A THREE-INCH  TELESCOPE. 


355.  Licetus 

371.  Piccolomini 

386. 

Pitiscus 

356.  Cuvier 

372.  Fracastorius 

387. 

Hommel 

357.  Clairant 

373.  Neander 

388. 

Vlacq 

338.  Maurolycus 

374.  Stiborius 

389- 

Rosenberger 

359.  Barocius 

375.  Reichenbach 

390. 

Nearchus 

360.  Bacon 

376.  Rheita 

39i- 

Hagecius 

361.  Buch 

377.  Fraunhofer 

392. 

Biela 

362.  Biisching 

378.  Vega 

393 

Nicolai 

363.  Gemma  Frisius 

379.  Marinus 

394- 

Lilly 

364.  Poisson 

380.  Oken 

395- 

Jacobi 

365.  Nonius 

381.  Pontecoulant 

396. 

Zach 

366.  Fernelius 

382.  Hanno 

397- 

Schomberger 

367.  Riccius 

383.  Fabricius 

398. 

Boguslawski 

368.  Rabbi  Levi 

384.  Metius 

399- 

Boussingault 

369.  Zagut 

385.  Steinheil 

400. 

Mutus 

370.  Lindenau 

The  beginner 

with  the  telescope  who  has 

read  or  heard 

of  ‘ mountains  ’ in  the  moon,  and  who  takes  his  first  look  at 
our  satellite  with  a view  of  examining  them,  will  certainly  be 
puzzled  by  the  spectacle  presented  to  his  gaze.  If  we  sup- 
pose the  moon  to  be  five  or  six  days  old,  and  that  he  is 
regarding  her  southern  horn  (or  upper  one,  as  seen  in  the 
telescope),  he  will  be  struck  by  the  fact  that  it  seems  to 
be  completely  honeycombed  by  circular  or  elliptical  holes, 
surrounded  by  ridges,  their  walls  breaking  into  each  other, 
and  the  depressions  themselves  being  confluent  in  all  direc- 
tions. A little  thought  and  attention  will  reveal  the  fact 
that  these  are  volcanic  craters  on  the  plains,  surrounded 
by  cliffs,  with,  in  many  cases,  conical  hills  rising  from  their 
centre,  which  we  are  viewing  from  above,  as  though,  in 
fact,  we  were  looking  down  upon  them  from  the  car  of  a 
balloon  suspended  at  a tremendous  height  above  them.  In 
the  case  of  those  close  to  the  terminator,  the  sun  is  just 
rising,  and  their  depressed  plains  or  cup-shaped  interiors 
are  still  plunged  in  the  blackness  of  night  ; while  the  more 
elevated  cliffs  surrounding  them  have  already  caught  the 
sun’s  rays,  and  stand  prominently  out  of  the  darkness.  The 
words  ‘ blackness  of  night,’  which  I have  just  used,  are 
peculiarly  appropriate  in  the  case  of  the  moon,  inasmuch  as, 


THE  MOON. 


21 


from  her  absence  of  atmosphere,  light  is  not  scattered,  as  it 
is  upon  the  earth,  and  everything  that  is  not  in  brilliant  sun- 
shine is  in  total  darkness.  The  observant  student  may 
possibly  demur  to  this  statement  when  he  notices  that,  close 
to  the  terminator,  the  light  fades  .gradually  ; but  he  must 
bear  in  mind  that  the  sun  is  rising  very  slowly  at  this  part  of 
the  moon’s  surface,  and  that  only  a small  portion  of  his  disc 
(from  which,  moreover,  his  rays  fall  very  obliquely)  is  above 
the  horizon  there.  One  notable  effect  of  the  absence  of  air, 
and  the  consequent  brilliant  lights  and  jet-black  shadow  son 
our  satellite,  is,  that  telescopic  power  tells  upon  her  surface 
to  an  extent  incomparably  greater  than  it  does  in  the  case 
of  any  other  body  in  the  sky.  Let  us  assume  that  we  are 
employing  a power  of  160.  Well,  this  shows  us  the  moon 
as  she  would  appear  to  the  naked  eye  were  she  only  1,468 
miles  from  the  surface  of  the  earth — a pretty  long  distance 
truly;  but  when  we  consider  that  Mont  Blanc  is  discernible 
by  unassisted  vision  from  Lyons,  100  miles  off,  through  all 
the  thickness  of  the  intervening  terrestrial  atmospheric 
vapour,  we  shall  gain  some  notion  of  what  this  represents  in 
the  case  of  the  airless  moon,  with  her  brilliant  lights  and 
inky  shadows.  A power  of  250  will  bring  her  seemingly 
within  939  miles  of  us:  but  no  useful  purpose  will  be  attained 
by  the  employment  of  such  magnification  (for  seleno-graphi- 
cal  purposes)  with  a three-inch  telescope.  In  our  subsequent 
sketches  160  is  the  highest  power  that  was  ever  used.  The 
nature  and  character  of  the  objects  it  will  reveal  will  become 
apparent  in  the  description  of  them  which  will  follow. 


Night  One. 

In  commencing  our  examination  of  some  of  the  typical 
and  more  remarkable  objects  on  the  moon’s  surface,  I will 
suppose  that  she  is  between  three  and  four  days  old.  Arming, 
then,  our  three-inch  telescope  with  a power  of  120,  we  pro- 
ceed to.  direct  it  to  her  face  ; and  a very  remarkable  spectacle 
it  is  which  will  present  itself  to  the  student  making  his 


22  HOURS  WITH  A THREE-INCH  TELESCOPE. 


maiden  observational  essay  on  our  satellite.  He  will  first 
be  struck  by  the  number  of  ring-plains,  of  which  I have 
briefly  spoken  above,  between  the  circular  bright  western 
limb  of  the  moon  and  the  ‘terminator;’  by  which  name, 
as  I have  previously  explained,  the  boundary  of  light  and 
darkness  is  known.  The  Sea  of  Conflicts  (A  in  our  map) 
and  part  of  the  Sea  of  Fertility  (X)  will  also  strike  his  eye. 
Before  proceeding,  however,  to  scrutinise  the  various  objects 
contained  within  the  bright  crescent  of  the  moon,  it  will  be 
interesting  to  shift  her  image  in  the  field  of  view  of  the  tele- 
scope. If  this  be  done,  it  will  be  found  that  the  whole  of 
the  moon  is  visible  ; the  dark  limb  looking  like  a very  ghost 
on  the  black  background  of  the  sky.  Moreover,  if  the  at- 
mospheric conditions  are  favourable,  a certain  amount  of 
detail  will  be  readily  seen  upon  this  dark  portion  of  the 
moon,  a bright  spot,  Aristarchus  (148  in  our  map),  and  a 
dark  one,  Grimaldi  (272),  being  the  most  conspicuous  objects. 
I may  shortly  say  here,  with  reference  to  this  phenomenon, 
that  it  is  the  effect  of  earth-shine.  Five  minutes’  study  of 
the  diagram  illustrating  the  changes  of  the  moon  which 
appears  in  every  elementary  work  on  astronomy  that  has 
ever  been  written,  will  show  that  when  the  moon  is  new  to 
the  earth,  the  earth  is  full  to  the  moon.  Moreover,  we  pre- 
sent a disc  to  our  satellite  more  than  thirteen  times  the  size 
of  that  wThich  she  exhibits  to  us,  and  hence  it  will  be  seen 
that  the  amount  of  light  we  send  her  at  the  time  of  her 
conjunction  (or  wdien  she  is  ‘new’)  must  be  very  con- 
siderable. Of  course,  as  the  moon  waxes  to  us,  we  wane  to 
her,  so  that  it  is  only  during  the  first  and  last  few  days  of 
every  lunation  that  this  earth-shine  renders  the  dark  side  of 
the  moon  visible.  Having  satisfied  ourselves  as  to  its  visi- 
bility, we  will  return  to  the  illuminated  crescent.  Now,  the 
craters  and  plains  visible  at  the  time  of  which  I am  speaking 
all  present,  more  or  less,  an  elliptical  outline,  the  ellipticity 
becoming  more  and  more  marked  as  we  approach  the  bright 
limb.  If  the  student  will  regard  a terrestrial  globe  from  a 
little  distance,  he  will  at  once  understand  that  this  is  an 


THE  MOON. 


23 


effect  of  perspective.  In  fact,  while  the  Sea  of  Conflicts  (A) 
seems  to  have  its  major  axis  north  and  south,  it  in  reality 
lies  from  east  to  west  ; this  great,  dark  plain  measuring 
only  281  miles  from  north  to  south,  and  355  miles  from 
east  to  west.  I have  called  it  a plain,  but  a little  attention 
will  show  undulating  ridges  on  parts  of  its  surface.  Its 
greenish  grey  tint  will  be  noted,  too.  To  the  east  of  this 
‘ sea,’  Picard  (4)  will  be  seen.  To  the  west  of  this  is  a white 
spot,  which  is  a rather  mysterious  object,  having  been  seen 
to  present  the  most  varying  appearances.  North-east  of 
Condorcet  (5)  is  the  Promontorium  Agarum,  a kind  of  pen- 
insula projecting  into  the  Mare.  This  is  a striking  object 
when  the  moon  is  nearly  sixteen  days  old.  Cleomedes  (12) 
is  a fine  formation,  about  seventy-eight  miles  in  diameter.  It 
has  a trifid  mountain  in  its  interior.  On  its  eastern  wall  is 
situated  a very  deep  crater  plain,  Tralles  (13  in  the  map). 
There  is  a central  mountain  on  the  floor  of  this,  too. 
Endymion  (27)  is  a circular  plain  (elliptical  as  it  appears  in 
the  telescope).  Its  western  wall  rises  in  places  to  a height 
of  upwards  of  15,000  feet.  Directing  our 
instrument  now  towards  the  southern  half  of 
the  lunar  crescent,  we  arrive  at  Langrenus 
(338)  and  Vendelinus  (339),  the  former  a 
splendid  object,  with  a bright  central  hill. 

And  now  we  come  to  that  grand  object, 

Petavius,  which,  as  illustrating  several  typical 
lunar  features,  I have  here  drawn. 

As  seen  in  a three-inch  telescope  with  a 
power  of  120,  the  moon’s  age  being  3^24  days, 
it  will  be  noted  how  the  wall  is  divided 
by  narrow  valleys.  The  mountain  in  the 
convex  interior  is  nearly  5,600  feet  high  ; and  from  this  a 
straight  dark  line,  or  ‘ rill,’  will  be  seen  to  extend  in  a south- 
easterly direction  to  the  wall.  These  rills,  as  they  have  been 
called,  are  very  numerous  on  the  moon  ; but  few  are  so  con- 
spicuous as  the  one  of  which  I am  speaking.  They  appear 
to  be  exceedingly  deep  ravines,  clefts,  or  cracks  ; but  they 


Fig.  7. — Petavius 
Moon’s  Age,  3*24 
days. 


24  HOURS  WITH  A THREE-INCH  TELESCOPE. 


are,  undoubtedly,  the  most  inexplicable  of  all  lunar  objects. 
Sometimes  they  pass  through  wall  and  plain  indifferently  ; 
at  others,  they  seem  to  stop  short  at  an  object,  but  to  re- 
appear on  the  other  side  of  it.  Moreover,  they  occasionally 
intersect.  I shall  have  more  to  say  of  them  as  I proceed. 
Before  concluding  to-night’s  work,  the  attention  of  the 
young  observer  may  be  directed  to  one  or  two  points  of  the 
Leibnitz  Mountains  (259),  just  coming  into  sunlight,  and 
shining  like  stars  close  to  the  southern  cusp  of  the  moon. 


Night  Two. 

Our  first  essay  in  the  examination  of  the  lunar  surface 
was  supposed  to  be  made  when  the  moon  was  between  three 
and  four  days  old.  To-night  I will  imagine  that  her  age 
has  increased,  and  is  about  six  days.  The  first  thing  which 
will  strike  the  attentive  student  is  the  changed  aspect,  under 
the  more  vertical  light  of  the  sun,  of  the  formations  he  has 
observed  at  an  earlier  date  in  the  lunation.  Objects  near 
the  moon’s  western  limb,  which,  lit  laterally  by  the  rising 
sun,  cast  black  shadows,  and  so  revealed  their  configurations 
distinctly,  are  now  illuminated  (like  the  ‘ depths  of  the  sea,’ 
in  the  famous  prize  poem)  by  ‘ the  sun’s  perpendicular  rays,’ 
and  are  converted  into  mere  bright  blotches  upon  a darker 
background.  A strange  formation  which  was  close  to  the 
terminator  at  the  epoch  of  our  last  observation,  so  curiously 
illustrates  the  change  of  aspect  induced  by  varying  illumi- 
nation, that  I give  three  illustrations-  of  it  as  seen  in  the 
waxing,  full,  and  waning  moon  at  the  ages  given  under  the 
respective  drawings.  It  is  numbered  327  in  our  map,  and 
is  called  Messier,  presumably  from  its  resemblance  to  a 
comet  ; the  French  astronomer,  after  whom  it  is  named, 
having  been,  as  is  pretty  well  known,  one  of  the  keenest 
searchers  for  and  discoverers  of  comets  of  the  last  century. 

The  two  slightly  diverging  streaks  which  seem  to  radiate 
from  the  right  hand,  or  eastern  of  the  two  craters  (‘  Messier 
A ’),  appear  almost  artificial  in  their  regularity.  The  most 


THE  MOON. 


2 


curious  thing,  however,  in  connection  with  these  two  craters 
is  this  : that  Madler,  as  the  result  of  a large  number  of  ob- 


Fig.  8. — Messier.  Moon’s  Age,  3*95  days.  Fig.  9. — Messier.  Full  Moon. 


Fig.  10. — Messier.  Moon’s  Age,  17 ‘8  days. 


servations,  called  pointed  attention  to  their  precise  similarity 
in  size,  form,  depth,  and  brightness.  A glance  at  either  of 
our  drawings  made  at  the  telescope  at  the  epochs  specified 
will  suffice  to  show  that  they  now  differ  widely  in  this  respect : 
that  Messier  itself  (the  western  one)  is  decidedly  smaller 
than  "Messier  A,  and  that  their  major  axes  lie  approximately 
at  right  angles  to  each  other.  The  young  observer  should 
try  to  view  this  formation  under  the  same  illumination  as  I 
myself  did  in  making  the  third  of  the  above  sketches  ; the 
long  peaked  shadows  revealing  curiously  the  structure  of 
the  crater  walls  which  cast 
them.  Messier  itself  is 
about  nine  miles  in  dia- 
meter. The  southern  ex- 
tremity of  the  Sea  of  Nectar 
(V)  terminates  in  a kind  of 
bay,  known  as  Fracastorius 
(372). 

Under  this  illumination 
Fracastorius  looks  like  what  Fig"  Age. 

I have  called  above  a bay. 

If,  however,  it  be  observed  when  quite  close  to  the 
terminator  (preferably  in  the  waning  moon),  it  will  be 


26  HOURS  WITH  A THREE-INCH  TELESCOPE. 


seen  as  a complete  circle,  the  northern  part  of  it  con- 
sisting of  low  detached  blocks.  South  of  it  is  a very  fine 
object,  the  grand  ring- plain  Piccolomini  (371),  about  57-^ 
miles  in  diameter.  Between  this  and  Frascastorius  the  moon 
is  very  mountainous.  South  of  Piccolomini  lie  a number  of 
craters  and  ring-plains,  whose  names  may  be  learned  from 
our  map.  Starting  now  from  the  north  side  of  the  Sea  of 
Nectar  we  find  an  interesting  pair  of  craters,  Isidore  and 
Capella  (323  and  324) ; and  crossing  the  Sea  of  Tranquillity 
from  south  to  north  we  arrive  at  a group  of  craters,  Romer 
(52),  Littrow  (55),  Maraldi  (56),  and  Vitruvius  (57).  A 

little  range  of  mountains  of 
the  ordinary  terrestrial  type, 
called  Mount  Argseus  (58), 
will  be  noted  just  on  the  Sea 
of  Tranquillity.  On  the 
north-west  boundary  of  the 
Sea  of  Serenity  (H)  lies  one 
of  the  largest  ring-plains  in 
the  moon,  Posidonius  (54), 
some  62  miles  in  diameter. 
There  is  a fine  central  crater 
in  this  formation,  and  it 
would  form  an  instructive 
exercise  for  the  incipient 
selenographer  who  can  draw, 
to  try  and  sketch  some  of  the 
details  which  abound  in  this 
fine  object.  Atlas  (28)  and 
Hercules  (29)  here  shown 
are  two  noble  walled  plains 
or  depressions,  55  miles  and 
46  miles  broad  respectively. 
It  will  be  noted  that  while 
the  most  conspicuous  object 
in  the  interior  of  Atlas  is  a mountain,  in  Hercules  it  is  a 
crater.  Glancing  at  Pliny  (61),  a fine  terraced  ring,  full  of 


Fig.  12. — Atlas  and  Hercules. 
Moon’s  Age,  5 '65  days. 


Fig.  13. — Catherine,  Cyrillus,  and 
Theophilus.  Moon’s  Age,  5*65  days. 


THE  MOON. 


27 


little  hills,  on  our  way  southward  again,  we  will  conclude 
our  night’s  work  by  the  examination  of  that  noble  triple 
group,  Theophilus,  Cyrillus,  and  Catherine  (319,  320,  321). 
The  study  of  the  connection  between  these  grand  objects 
and  of  the  way  in  which  they  are  connected  supplies  us 
with  a key  to  the  chronology  of  this  part  of  the  lunar 
surface.  The  valley  connecting  Catherine  and  Cyrillus  will 
be  observed,  as  also  the  way  in  which  the  wall  of  Cyrillus 
has  been  intruded  on  by  Theophilus. 

Little  or  no  detail  is  observable  in  Catherine  when  so 
near  the  terminator,  but  the  shape  of  the  shadows  cast  into 
its  interior  reveals  that  of  the  ridges  and  peaks  causing 
them.  Cyrillus  will  be  seen  to  be  more  trapezoidal  than 
circular,  and  the  two  mountains  in  its  centre  and  the  con- 
spicuous crater  on  its  wall  will  at  once  arrest  the  eye. 
Theophilus  is  the  deepest  crater  in  the  moon,  the  walls 
being  in  places  18,000  feet  above  the  level  of  the  bottom. 
Its  diameter  is  nearly  64  miles.  Necessarily  its  sides  are 
brilliantly  illuminated  by  the  rising  sun  when  the  interior 
is  plunged  in  the  blackest  night,  and  at  about  the  fifth  day 
of  the  moon’s  age  it  may  be  seen  projecting  beyond  the 
terminator  into  the  darkness  of  the  seemingly  surrounding 
sky  as  a brilliant  ring.  Sharp-sighted  people  can  detect  this 
without  any  optical  aid. 

Night  Three. 

Advancing  sunlight  is  now  bringing  into  view  a highly 
complicated  mass  of  walled  plains  and  craters  in  the  south- 
western quadrant  of  the  moon  ; and  with  some  of  the  more 
notable  among  them  we  will  begin  our  work  to-night. 
Maurolycus  (358  in  our  map)  is  a splendid  object  about  the 
time  of  the  moon’s  first  quarter.  The  great  complexity  of 
the  wall  will  attract  the  attention  of  the  observer.  A few 
crater  pits  may  be  detected  with  the  instrument  we  are 
employing  on  the  walls,  as  well  as  on  the  floor  of  Mauro- 
lycus, and  there  are  numerous  hills  on  the  latter  also  visible 


28  HOURS  WITH  A THREE-INCH  TELESCOPE. 


under  favourable  illumination.  Another  splendid  object  in 
this  neighbourhood  is  Stofler  (354),  but  the  inside  of  this  is 
very  much  more  level  and  undisturbed  than  that  of  its 
neighbour.  The  system  of  bright  streaks  radiating  from 
Tycho  (previously  referred  to  on  p.  16)  passes  over  this 
region,  with  the  curious  result  that  the  bold  and  most  con- 
spicuous formations  of  which  I am  speaking  to  all  intents 
and  purposes  disappear  at  full  moon  altogether  ! In  Walter 
(200),  Regiomontanus  (201),  and  Purbach  (202)  we  have 
an  instance  of  three  crater  plains  in  connection  with  each 
other,  and  lying,  approximately,  north  and  south  of  each 
other,  one  example  of  which  we  have  already  seen  in 
Theophilus,  Cyrillus,  and  Catherine,  and  another  of  which 
we  are  immediately  to  examine  in  Arzachel,  Alphonsus,  and 
Ptolemy.  North-east  of  Purbach  lies  Thebit  (203),  a crater 


Arzachel  is  about  65 ^ miles  in  diameter,  with  terraced 
walls,  diversified  by  clefts  and  craters.  Alphonsus  is  83  miles 
across,  and  has  very  complicated  walls.  The  northern  one 


Fig.  14. — Arzachel,  Alphonsus, 
and  Ptolemy. 


well  worth  examining,  as  atten- 
tive inspection  will  show  that 
another  crater  has  burst  the 
original  wall,  and  has  itself  in 
turn  been  intruded  on  by  a 
more  minute  one  still.  Here, 
again,  we  are  able  to  trace  the 
chronological  sequence  of  the 
successive  eruptions.  A strange 
formation,  known  as  ‘ Straight 
wall,’  but  looking  (when  the 
moon  is  eight  or  nine  days  old) 
like  a stag’s  horn  on  the  top  of 
an  alpenstock,  will  be  noted 
not  far  to  the  east  of  Thebit. 
And  now  we  arrive  at  that 
truly  superb  triple  system, 
Arzachel  (204),  Alphonsus 
(207),  and  Ptolemy  (208). 


THE  MOON. 


29 


opens  by  clefts  and  valleys  into  Ptolemy — an  enormous 
walled  plain  of  115  miles  in  diameter.  The  conspicuous 
crater  in  its  floor  will  at  once  strike  the  eye.  In  Alphonsus, 
the  chief  object  in  the  interior  is  a mountain  ; while  in 
Arzachel  both  a mountain  and  a crater  will  be  noted  by  the 
observer.  In  our  sketch  above,  Alpetragius  (205)  will  be 
seen  to  have  its  interior  w'holly  immersed  in  shadow.  This 
beautiful  crater  is  about  27  miles  across,  and  is  so  compara- 
tively deep  as  to  be  only  free  from  shadow7  for  less  than  a 
wreek  during  the  entire  lunation.  Herschel  (212)  is  a fine 
ring-plain,  24  miles  in  diameter,  with  a central  mountain. 
Rhseticus  (104)  is  noticeable  as  lying  actually  on  the  lunar 
equator.  Godin  (103)  and  Agrippa  (102),  two  ring-plains 
of  23  and  27  miles  in  diameter  respectively,  are  fine  objects 
vrhen  seen  near  the  terminator.  The  observer  should  care- 
fully examine  that  curious  object  Hyginus  (93)  and  its 
neighbourhood  about  the  time  of  the  first  quarter,  employ- 
ing for  this  purpose  as  high  a power  as  his  telescope  will 
bear  (say  160).  He  will  note  the  curious  rill  running  right 
through  the  crater,  the  snail-shaped  or  spiral  mountain  just 
to  the  north  of  it,  a brilliant  ridge  to  the  west  of  this  again, 
and  so  on.  Hereabouts  it  is  that  the  alleged  discovery  of 
the  depression  known  as  ‘ Hyginus  N.’  w7as  made.  The 
incipient  observer  with  a three-inch  telescope  must  not,  hov7- 
ever,  blame  either  himself  or  his  instrument  should  he  fail 
to  distinguish  this  mysterious  object.  Manilius  (95)  is  a 
fine  object  under  proper  illumination.  Its  diameter  is  25^ 
miles.  The  Sea  of  Serenity,  at  vdiich  we  now  arrive  (H), 
contains  numerous  objects  to  reward  the  observer.  Among 
them  is  the  curious  one,  Linne  (74),  which,  save  when 
almost  on  the  terminator,  presents  the  appearance  of  a 
minute  v'hitish  cloud,  or  little  smudge  of  light.  It  may  be 
found  on  a line  drawn  from  Pliny  (61)  through  Bessel  (73). 
The  two  splendid  craters,  Eudoxus  (77)  and  Aristotle  (78) 
here  drawn,  present  a grand  spectacle  when  near  the 
boundary  of  light  and  darkness,  either  with  a waxing  or  a 
waning  moon.  My  own  sketch  on  the  next  page  was  made 


30  HOURS  WITH  A THREE-INCH  TELESCOPE. 


when  the  sun  was  rather  too  high  above  their  horizon.  Under 
suitable  illumination  Aristotle  will  be  seen  to  be  surrounded 
by  radiating  chains  of  hills.  Cassini  (81)  is  a curious  object 
about  the  time  of  the  moon’s  first  quarter.  Its  diameter  is 
about  36  miles,  and  it  contains  a ring-plain,  some  nine  miles 
across,  within  it.  The  edge  of  the  ring  of  Cassini  must  be 
considerably  serrated  or  cut  into  peaks  and  spires.  With 
Archimedes  (120),  Aristillus  (83),  and  Autolycus  (84)  we 
shall  conclude  our  work  to-night.  The  examination  of  the 
region  in  which  they  are  situated  may  well  afford  us  an 
entire  evening’s  occupation  on  a future  occasion. 


Fig.  15. — Eudoxus  and  Aristotle.  Fig.  16. — Autolycus.  Aristillus, 

and  Archimedes. 


Archimedes  is  a comparatively  shallow  ring-plain  of  50 
miles  in  diameter.  The  inside,  with  our  instrumental  means, 
will  appear  quite  smooth  ; but  powerful  telescopes  show 
minute  craterlets  and  spots  in  it.  When,  however,  this  great 
plain  is  fully  illuminated,  a three-inch  telescope  will  show 
that  the  floor  is  striped  or  streaked  with  alternate  light  and 
darker  bands.  Archimedes  is  a grand  object  when  the  sun 
is  either  rising  or  setting  upon  it.  Aristillus,  34  miles  across, 
has  a central  mountain,  shown  in  our  sketch.  Under  rather 
more  oblique  illumination,  ridges,  like  lava  streams,  may  be 
seen  radiating  from  the  outer  ring.  Autolycus,  23  miles  in 
diameter,  is  tolerably  deep,  but  calls  for  no  more  special 
description  here. 


THE  MOON. 


3i 


Night  Four. 

To  the  north-west  of  Cassini  (described  on  p.  30)  lie  the 
Lunar  Alps  (80  in  our  map),  a range  of  mountains  possessing 
a much  more  terrestrial  character  than  the  majority  of  objects 
visible  on  the  moon’s  surface.  They  start  from  the  neigh- 
bourhood of  Cassini,  and  extend  with  a very  remarkable 
interruption,  immediately  to  be  spoken  of,  nearly,  if  not 
quite,  to  Plato.  The  interruption  of  which  I have  just 
spoken  takes  the  form  of  an  enormous  wedge-shaped  valley, 
between  eighty  and  ninety  miles  long,  and  varying  in  width 
from  three  and  a half  to  six  miles.  Our  sketch  represents 
this  region  as  it  appears  with  a power  of  120,  the  age  of  the 
moon  being  7-58  days. 


Fig.  17. — The  Valley  of  the  Alps,  and  Sunrise  on  Plato. 
Moon’s  Age,  7*58  days. 


The  eastern  side  of  the  valley  is  the  steeper  of  the  two. 
The  highest  of  the  mountain  masses  lie  to  the  west  of  the 
huge  cleft,  the  eastern  range,  however,  increasing  in  magni- 
tude as  it  approaches  Plato  (132).  The  sun  was  just  rising 
on  this  last-named  superb  formation  at  the  time  the  drawing 
above  was  made  ; and  its  interior,  as  will  be  seen,  was 
plunged  in  the  blackness  of  night.  While  scrutinising  this 
part  of  the  moon’s  surface,  the  student  may  direct  his  at- 
tention to  the  two  interesting  ring-plains  to  the  north — 


32  HOURS  WITH  A THREE-INCH  TELESCOPE. 

Archytas  (46)  and  Timseus  (170).  Plato  itself,  and  its 
vicinity,  present  a most  interesting  region  for  examination 
during  the  seventh,  eighth,  ninth,  and  tenth  days  of  the 
moon’s  age  ; as  they  do  (though  at  a most  inconvenient 
hour)  when  she  is  twenty-one  or  twenty-two  days  old.  This 
great  walled  plain  measures  sixty  miles  across,  and  is  notable, 
when  fully  illuminated,  for  its  steel-grey  tint.  Its  surround 
ing  wall  is  broken  in  places,  and  exhibits  very  little  of  that 
series  of  descents  in  terraces  which  we  shall  find  by-and-by 
in  Eratosthenes,  Copernicus,  &c.  A variety  of  streaks  and 
spots  have  been  detected  upon  the  very  level  floor  by  the 
aid  of  large  and  powerful  telescopes  ; but  by  far  the  larger 
proportion  of  these  details  are  hopelessly  beyond  the  reach 
of  the  observer  with  such  an  instrument  as  that  whose  use 
is  presupposed.  Under  suitable  illumination,  the  shadows 
of  three  huge  peaks  on  the  western  wall  will  be  seen  cast 
upon  the  floor  ; as  will  that  of  an  even  higher  one  from  the 
eastern  wall  out  on  to  the  very  broken  surface  of  the  Mare 
beyond.  It  is,  so  far,  an  inexplicable  fact,  that,  as  the  sun 
rises  on  the  interior  plain  of  Plato,  it  follows  the  usual  law 
of  getting  brighter  until  the  sun  has  attained  an  altitude  of 
200,  or  thereabouts  ; after  which  it  darkens  very  notably 
and  perceptibly  until  shortly  after  full  moon.  South  of 
Plato  stands  that  absolutely  isolated  peak,  Pico(i3i),  in  the 
dark  grey  Sea  of  Showers.  As  it  is  some  8,000  feet  in  height, 
it  casts  a tremendously  long  shadow  under  the  oblique 
illumination  either  of  sunrise  or  sunset,  and  forms  a most 
conspicuous  object.  Timocharis  (121)  is  worth  looking  at 
for  its  terraced  wall.  The  glorious  mountain  chain  of  the 
Apennines  (85,  87,  92,  in  our  map)  presents,  like  the  Alps 
of  which  I have  spoken  above,  a very  decidedly  more 
terrestrial  character  than  the  vast  majority  of  lunar  objects. 
We  may  regard  this  superb  range  as  starting  in  the  north 
from  Cape  Hadley  (87),  which  rises  more  than  15,000  feet 
from  the  plain  at  its  base,  although  they  will  be  seen  to  trend 
in  a south-westerly  direction  from  it.  Following  them, 
however,  in  their  eastern  course  round  the  Sea  of  Showers, 


THE  MOON. 


33 


we  come  to  Bradley  (89),  a mountain  13,600  feet  in  height, 
and  to  Huyghens  (90),  the  loftiest  of  their  peaks,  attaining 
an  altitude  of  some  20,000  feet.  The  spectacle  presented 
by  this  range  of  mountains — for  the  observation  of  which  a 
power  of  160  may  be  employed  on  a fine  night — with  their 
glittering  and  corrugated  highlands,  and  the  serrated 
shadows  cast  by  their  peaks  on  the  plain  beneath,  is  a 
wonderfully  beautiful  one,  and  will  repay  the  most  earnest 
attention  the  student  can  give  to  it.  The  projection  of  this 
noble  ridge  beyond  the  illuminated  part  of  the  moon,  about 
the  time  of  first  quarter,  is  easily  discern'ble  with  the 
naked  eye  by  moderately  sharp-sighted  people.  It  may  be 
held  to  terminate  with  Eratosthenes  (no),  the  description 
of  which,  however,  I must  reserve  for  our  succeeding  night. 


Night  Five. 


Eratosthenes,  of  which  I spoke  at  the  conclusion  of  our 
fourth  night’s  work  as  terminating  the  magnificent  chain  of 
the  lunar  Apennines,  pre- 
sents a beautiful  spectacle 
about  the  ninth  day  of  the 
moon’s  age.  The  accom- 
panying drawing  was  made 
with  a power  of  160,  when 
the  moon’s  age  was  9^23 
days.  The  diameter  of  this 
finely  terraced  formation  is 
about  thirty-seven  and  a half 
miles,  and  its  walls  will  be 
seen  to  be  very  rugged.  The 
three  central  peaks,  too,  are 
conspicuously  shown  under  this  illumination.  It  is  curious 
that  a formation  presenting  such  strongly  marked  features 
when  lighted  obliquely  by  the  rising  or  setting  sun,  should 
be  by  no  means  easy  to  find  at  full  moon.  South-east 
of  Eratosthenes  will  be  noted  a deep  mountain  range 

D 


Fig.  18. — Eratosthenes.  Moon’s  Age, 
9*23  days. 


34  HOURS  WITH  A THREE-INCH  TELESCOPE. 


terminating  in  a ring-plain,  whose  walls  are  only  some  130  feet 
or  so  high.  Hence  it  is  only  visible  during  a short  period 
of  favourable  illumination,  and  forms  a very  severe  test  of 
the  defining  power  of  a three-inch  telescope,  and  of  the  keen- 
ness of  the  observer’s  vision.  The  height  of  the  connecting 
ridge  of  mountains  is  some  4,470  feet.  As  Ben  Nevis  is 
4,406  feet,  and  Snowdon  only  3,571  feet  high,  this  may 
suffice  to  furnish  a scale  whereby  the  student  may  estimate 
the  dimensions  of  the  leading  features  of  this  neighbourhood. 
Schroter  (106),  or  rather,  its  northern  vicinity,  should  be 
carefully  looked  at  when  near  to  the  terminator,  for  the 
strange  system  of  ramparts  sloping  off  on  either  side  of  a 
central  one,  which  Gruithuisen  believed  to  be  artificial,  but 
which,  in  reality,  consists  of  a series  of  parallel  valleys. 
Parry  (217),  Bonpland  (218),  and  Fra  Mauro  (219)  are 
more  or  less  imperfect  ring-plains,  which  present  a curious 
appearance  when  pretty  near  the  terminator.  Pitatus  (186) 
and  Hesiod  (187)  are  a pair  of  huge  craters — or  rather 
ring-plains — connected  by  a pass.  The  northern  wall  of 
the  former  will  be  seen  to  be  imperfect,  while  the  southern 
wall  is  separated  from  Tycho,  which  we  are  immediately  to 
examine,  by  a rugged  mass  of  mountain  peaks.  The  two 
most  notable  peculiarities  in  Hesiod  are,  a central  crater  in 
the  floor,  and  a cleft  (shown  in  our  map),  running  into  the 
Sea  of  Clouds.  And  now  we  arrive  at  what  has  been  aptlv 
called  by  the  late  lamented  Prebendary  ebb  ‘ the  metro- 
politan crater  of  the  moon,’  Tycho  (180),  reference  to  the 
system  of  streaks  emanating  from  which  has  been  once  or 
twice  previously  made.  This  splendid  lormation,  visible  as 
a white  spot  to  the  naked  eye  at  full  moon,  measures  fifty- 
four  miles  and  a quarter  across,  and  exhibits  an  elaborately 
terraced  wall,  some  16,000  feet  high,  on  the  east  side,  and 
upwards  of  17,000  feet  in  height  in  its  western  portion.  In 
fig.  19  1 have  purposely  abstained  from  any  attempt  to 
delineate  the  extremely  disturbed  and  rugged  region  sur- 
rounding Tycho,  confining  myself  strict  ly  to  drawing  the 
crater  itself. 


THE  MOON. 


35 


The  central  hill  shown  below  is  between  5,000  and  6,000 
feet  high,  its  conical  shadow  being  very  conspicuous  at  the 
time  our  drawing  was  made.  The 
inextricable  mass  of  craters,  hil- 
locks, pits,  and  irregularities  in 
the  immediate  neighbourhood  of 
Tycho,  almost  defies  any  attempt 
to  draw  or  map  it.  The  wonder- 
ful system  of  light-rays,  radiating 
from  this  great  crater,  extends 
over  at  least  a quarter  of  the 
visible  hemisphere  of  the  moon.  Flff' I9'— T9^°<iays!oon  s Age’ 
Some  of  them  may  be  traced 

to  the  southern  limb,  and  doubtless  extend  beyond  it 
into  that  hemisphere  which  is  always  hidden  from  the 
terrestrial  observer.  One  tremendous  ray  passes  through 
the  Sea  of  Serenity,  the  craters  70  and  73  in  our  map  lying 
upon  it.  Another  very  conspicuous  one  connects  Tycho 
with  the  interesting  formation  Bullialdus  (213).  It  is  a 
notable  fact,  that  while  these  rays,  in  nearly  every  other 
instance,  pursue  their  course  through  hill,  valley,  crater,  and 
plain,  without  deviation  or  interruption,  the  crater  Saussure 
(196)  has  deflected  one  of  them,  and  caused  it  apparently  to 
bend  round  its  southern  wall.  What  these  stupendous  bands 
are,  can  only  be  regarded,  at  present,  as  a mystery.  Nasmyth 
considers  them  to  be  cracks  filled  up  with  molten  lava  from 
the  moon’s  interior  ; but,  arguing  from  their  terrestrial 
analogues,  trap-dykes,  we  should  expect  to  find  them  pro- 
jecting, more  or  less,  above  parts  of  the  lunar  surface,  and, 
as  a necessary  consequence,  casting  shadows,  when  on,  or 
near,  the  terminator.  As  a matter  of  fact  we  find  them 
everywhere  absolutely  level  with  the  regions  which  they 
traverse.  Of  whatever  material  they  are  composed,  its 
reflective  power  must  be  very  high,  inasmuch  as  the  ray 
system  of  Tycho  traverses  the  (in  many  cases)  huge  and 
complicated  forma‘ions,  Sasserides  (183),  Gauricus  (185), 
Heinsius  (190),  Wilhelm  I.  (191),  Long^montanus  (192), 

d 2 


36  HOURS  WITH  A THREE-INCH  TELESCOPE. 

Clavius  (193),  Maginus  (195),  Orontius  (197),  Nasir-ed-din 
(iq8),  Lexell  (199),  Walter  (200),  Moretus  (262),  Stofler 
(354),  and  Maurolycus  (358),  all  of  which  are  most  con- 
spicuous objects  when  obliquely  lighted  ; but  which,  one 
and  all,  disappear  wholly  at  full  moon,  or  under  vertical 
illumination  ! The  late  Professor  Nichol,  amid  much 
which,  after  all,  amounted  merely  to  assertion,  did  point  out 
one  valuable  piece  of  evidence  furnished  by  these  rays  ; 
and  that  is,  the  proof  afforded  by  their  continuous  visibility, 
and  the  homogeneous  character  of  their  brightness  through- 
out their  course,  that  the  reflective  substance  of  which  they 
are  composed  is  absolutely  everywhere  uncovered.  Did 
anything  in  the  shape  of  vegetation,  for  example,  exist  in 
the  moon,  it  must  obscure  portions  of  these  light  streaks. 
That  they  pass  undimmed,  then,  from  their  origin  to  their 
termination,  shows  plainly  enough  that  they  traverse  ‘ a 
rocky  desert,  devoid  of  life  or  living  thing.’  Here  our  night's 
work  may  cease.  We  shall  turn  our  telescope  on  Copernicus 
( 1 1 2)  as  soon  as  it  is  favourably  illuminated. 

Night  Six. 

When  the  moon  is  nine  or  ten  days  old,  the  Bay  or 
Rainbows  (P  in  our  map)  presents  a perfectly  charming 
spectacle  to  the  observer.  This  great,  dark,  semicircular 
area  appears  absolutely  level  in  the  instrument  we  are  using, 
but  is  surrounded  by  a mass  of  stupendous  cliffs.  It  mea- 
sures, from  Cape  La  Place  (134)  to  Cape  Heraclides  (135), 
nearly  125  miles.  Heraclides  rises  some  4,000  feet  above 
the  level  of  the  bay,  but  is  as  a mere  hillock  compared  with 
some  of  the  neighbouring  highlands.  As  we  travel  in  an 
easterly  direction  we  arrive  at  Sharp  (139),  15,000  feet  in 
height,  and  some  of  the  peaks  in  this  chain  probably  attain 
an  altitude  approaching  to  20,000  feet.  Nearly  due  south 
of  Cape  La  Place  lie  two  little,  but  exceedingly  deep  craters 
— the  eastern  one  of  which,  Helicon,  is  marked  129  in  the 
map.  And  now  we  arrive  at  a region  covered  with  systems 


THE  MOON. 


37 


of  light- streaks,  akin  to  those  described  on  p.  35  as  emanat- 
ing from  Tycho.  Euler  (125),  a fine  ring-plain,  19  miles 
in  diameter,  with  a central  peak,  is  the  centre  of  one  of 
these  systems  of  rays.  Tobias  Mayer  (117),  22  miles  across, 
is  an  interesting  object  under  suitable  illumination.  Of  all 
the  formations,  however,  in  this  region  of  the  lunar  surface, 
there  is  nothing  to  compare  with  that  superb  one,  Coper- 
nicus (1x2),  our  sketch  of  which 
was  taken  with  a power  of  160, 
when  the  moon’s  age  was  10 ‘2  7 
days.  This  magnificent  ring- 
plain  measures  56  miles  across. 

There  are,  altogether,  eight 
peaks  rising  from  the  interior — 
three  bright  ones,  and  four  less 
so.  With  the  instrument  em- 
ployed, however,  and  under  the 
conditions  of  illumination  then 
obtaining,  two  only  of  these 
were,  as  will  be  seen,  visible 
at  the  epoch  of  our  drawing. 

The  terraced  character  of  the 
wall  is  conspicuous  enough, 
even  in  a 3-in.  telescope,  as  is  the  disturbed  and  com- 
plicated character  of  the  region  immediately  surrounding 
it.  Twro  deep  craters  south  of  Copernicus,  approximating 
in  appearance  to  the  figure  8,  will  at  once  strike  the 
eye.  So  also  will  a conspicuous  peak  on  the  western 
wall,  which  is  between  11,000  and  12,000  ft.  high.  The 
somewfixat  angular  character  of  the  contour  of  the  wall  is 
well  seen  from  the  shadows  cast  towards  the  east.  Other 
features  will  strike  the  attentive  observer.  At  full  moon, 
Copernicus  is  seen  to  be  the  centre  of  a system  of 
light-streaks,  uniting  with  similar  ones  from  other  forma- 
tions to  wrhich  we  shall  hereafter  refer.  It  is  worthy  of  note 
that  the  streaks  extending  in  a westerly  direction  from 
Copernicus  are  the  most  numerous  ; though  those  which 


Fig.  20. — Copernicus. 
Moon’s  Age,  10*27  days. 


38  HOURS  WITH  A THREE-INCH  TELESCOPE. 


lie  towards  the  north  are  individually  more  conspicuous. 
There  is  an  enormous  number  of  tiny  craters  between 
Copernicus  and  Eratosthenes  (tio)  ; but  even  the  largest 
of  these  require  favourable  illumination  and  conditions  to 
be  seen  in  our  instrument.  Reinhold  (114),  31  miles  across, 
will  repay  scrutiny  while  the  telescope  is  turned  on  this  part 
of  the  mcon’s  visible  disc.  Euclid  (221)  and  Landsberg 
(222)  furnish  examples  of  craters  surrounded  by  a kind  of 
nimbus  or  light-ring.  This,  as  will  be  seen  on  examination, 
differs  in  appearance  from  the  streaks  emanating  from  Tycho, 

< 'opernicus,  Kepler,  and  Aristarchus.  Kepler  (144),  by  the 
way,  may  be  here  referred  to  as  a crater,  close  upon  22 
miles  across,  the  centre  of  a great  system  of  light-streaks, 
uniting  with  those  from  Copernicus.  Close  to  Euclid  lie 
the  Riphsean  Mountains  (220).  Under  oblique  illumina- 
tion they  stronglv  suggest  an  exaggerated,  or  caricatured, 
bas-relief  of  a llama  or  giraffe.  One  of  the  deepest  craters 
in  the  Sea  of  Clouds  is  Bullialdus  (213),  to  which  a light- 
streak  extends  (as  mentioned  on  page  35)  from  Tycho  (180). 
This  is  385  miles  across,  with  finely  terraced  walls  of  con- 
siderable breadth,  and  a fine  central  mountain  3,000  feet 
high.  The  considerable  crater  or  ring-plain,  breaking  into 
the  southern  wall,  too,  will  at  once  strike  the  eye,  while  a 
very  similar  one  (but  detached  from  Bullialdus  proper) 
will  be  noted  to  the  south  of  this  again.  Campanus  (226), 
a ring  30^  miles  across,  in  this  neighbourhood,  is  chiefly 
remarkable  for  the  darkness  of  its  interior.  Hainzel(237)  is 
a kind  of  pear-shaped  ring-plain,  55  miles  in  its  longest  dia- 
meter, with  high  and  precipitous  walls  rising  some  11.600  ft. 
in  places.  The  wall  of  Capuanus  (238),  too,  will  repay 
examination  under  suitable  illumination.  Capuanus  is  one 
of  the  comparatively  few  craters  that  remain  conspicuous 
and  identifiable  when  the  moon  is  full.  We  are  now  in  the 
neighbourhood  of  the  Sea  of  Moisture  (T  in  our  map).  The 
student  may  begin  his  examination  of  this  region  with  the 
large  bay  in  this  ‘sea,’  Hippalus  (225).  The  chief  interest, 
however,  attaching  to  this  locality  resides  in  the  wonderful 


T. HE  MOON. 


39 


system  of ‘rills,’  or  narrow  and  tortuous  clefts,  existing  to 
the  west  of  Hippalus.  The  majority  of  these  require  a large 
instrument  for  their  detection,  but  one  or  two  of  them  are 
within  the  reach  of  a three-inch  telescope  when  the  moon  is 
between  nine  and  ten  days  old.  The  formation  of  Vitello 
(229)  seems  to  afford  an  illustration  of  the  vulgar  phrase,  ‘a 
wheel  within  a wheel,’  inasmuch  as  the  outer  ring-plain  en- 
closes another  one,  from  the  interior  of  which  rises  a moun- 
tain, 1,600  ft.  or  1,700  ft.  high.  With  the  examination  of 
Gassendi  (232),  on  the  northern  boundary  of  the  Sea  of 
Moisture,  we  shall  conclude  another  night’s  work. 

Our  sketch  of  this  fine  and  interesting  formation  was 
made  with  a power  of  160,  the  moon  being  11-24  days  old, 
and  Gassendi  very  nearly  on  the 
terminator.  The  diameter  of  this 
great  walled  plain  is  fifty-five 
miles.  The  height  of  its  sur- 
rounding cliffs  varies  greatly  ; in 
places  they  rise  to  an  altitude  of 
some  10,000  feet,  while  towards 
the  south,  as  will  be  seen  in  the 
drawing  I give,  they  diminish  to 
a twentieth  part  of  that  height. 

It  is  worthy  of  remark  that  Madler 
asserts  that  the  floor  of  Gassendi 
is  in  its  northern  part  quite  2,000 
feet  above  the  level  of  the  almost 
adjoining  Sea  of  Moisture.  It  will 
be  observed  how  the  northern  part 
of  the  wall  has  been  destroyed  by  the  subsequent  eruption  in 
which  the  great  spoon-shaped  ring-plain  shown  was  formed. 
At  the  epoch  of  our  sketch,  the  three  central  mountain  masses, 
rising  from  the  principal  plain,  were  conspicuously  shown. 
It  will  be  seen  that  the  westernmost  of  these  is  the  largest 
and  highest,  the  tips  of  the  others  only  peeping,  as  it  were, 
out  of  its  shadow.  This  is  a formation  which  may  be  ad- 
vantageously studied  continuously  during  the  eleventh  and 


Fig.  21. —Gassendi. 
Moon’s  Age,  11*24  days. 


4o  HOURS  WITH  A THREE-INCH  TELESCOPE. 


twelfth  days  of  the  moon’s  age,  as  it  exhibits  so  many  com- 
plicated features  ; and  it  is  most  instructive  to  the  beginner 
to  note  how  these  come  into  view  and  alter  in  aspect  with 
advancing  sunlight.  Moreover,  the  student  should  observe 
it  in  different  states  of  the  moon’s  libration. 1 The  changes 
produced  in  the  aspect  of  formations  in  the  neighbourhood 
of  the  moon’s  limb  from  this  cause  are  most  striking  and 
remarkable. 

Night  Seven. 

The  light  of  the  rising  sun  continues  to  creep  over  the 
moon’s  disc,  and  we  are  rapidly  approaching  her  eastern 
limb  ; in  other  words,  she  is  now  entering  that  phase 
denominated  full  in  the  almanacs,  when  the  whole  of  her 
surface  which  is  turned  towards  the  earth  is  simultaneously 
visible.  For  reasons  before  stated,  however  (p.  16),  this  is 
the  very  worst  aspect  under  which  details  can  be  examined, 
or  even  identified  ; and  I shall,  therefore,  describe  the 
leading  formations  which  still  remain  to  be  spoken  of,  as 
they  appear  when  tolerably  near  the  terminator.  And  here 
I may  note  that  ring-plains  and  mountains  situated  on,  or 
very  near,  the  actual  visible  limb  of  the  moon,  are  seen  in  a 
much  more  natural  manner  by  the  terrestrial  observer  than 
those  more  centrally  placed  on  her  disc  ; since  they  are,  of 
course,  looked  at  much  more  sideways  ; like  our  own 
mountain  ranges  as  we  view  them  from  the  surface  of  the 
earth.  The  student  will  be  struck  with  this  if  he  will 
go  carefully  round  the  eastern  (and  especially  the  north- 
eastern) limb  of  the  moon  within  a day  or  two  of  her  being 
full.  It  is  time,  however,  that  we  began  our  examination  of 
such  individual  objects  as  offer  points  of  peculiar  interest. 
Beginning  from  the  south,  we  shall  be  struck  with  the 
Dorfel  Mountains  (246  in  our  map),  seen  in  profile  on  the 
actual  limb  of  the  moon.  The  three  most  conspicuous 

1 For  an  explanation  of  lunar  libration  see  The  Moon , by  the 
editor  of  Knozvledge  (Longmans  & Co.),  pp.  1 18  el  s?q. 


THE  MOON. 


4 


peaks  of  this  tremendous  range  are  believed  to  exceed 
26,000  feet  in  height.  The  highest  mountain  in  the  world, 
Mount  Everest,  in  the  Himalayas,  is  29,000  feet  in  altitude, 
but  did  this  bear  the  same  proportion  to  the  earth’s  diameter 
that  the  Dorfel  Mountains  do  to  the  moon’s,  then  would  it 
be  106,079  feet,  or  more  than  twenty  miles  in  perpendicular 
height.  In  this  neighbourhood  Phocylides  (242)  may  be 
looked  at  as  a considerable  walled  plain,  with  a flat  interior. 
I,  however,  mention  it  here  chiefly  as  a guide  to  that  curious 
object,  Wargentin  (243),  which  looks  like  an  extremely 
truncated  column,  some  54  miles  in  diameter.  Webb  aptly 
compares  this  to  ‘ a large,  thin  cheese.’  When  the  moon  is 
eleven  or  twelve  days  old,  Schickard  (239),  an  enormous 
walled  plain,  will  repay  scrutiny.  From  north  to  south  this 
measures  some  134  miles,  and  is  nearly  as  broad,  though, 
of  course,  it  is  considerably  foreshortened  as  we  view  it. 
The  interior  is  very  nearly  level,  but  a three-inch  telescope 
will  show  the  diversity  of  shade  which  characterises  it. 
Mersenius  (231)  is  a fine  ring-plain  more  than  41  miles 
across,  and  contains  various  small  hills,  craterlets,  <Scc., 
quite  beyond  the  power  of  our  instrument.  What  will  strike 
the  young  observer  is  the  aspect  of  its  floor,  which  is  con- 
vex, like  a watch-glass.  Just  as  Fracastorius  (372)  appears 
as  a bay  bounding  the  southern  extremity  of  the  Sea  ot 
Nectar  (p.  25),  so  does  Letronne  (224),  formed  by  the 
mountains  extending  from  Gassendi,  appear  at  one  ex- 
tremity of  the  Sea  of  Storms  (Q).  The  huge  dark  plain 
Grimaldi  (272)  is  nearly  148  miles  long  by  129  broad,  and 
would  have  ranked  as  a ‘ sea  ’ had  it  been  situated  near  the 
centre  of  the  moon,  instead  of  close  to  her  limb.  Grimaldi 
is  even  darker  than  Plato,  and,  as  I have  previously  re- 
marked (p.  22),  may  often  be  seen  on  the  dark  limb  of  the 
moon  when  illuminated  by  earthshine.  Riccioli  (273)  is 
another  enormous  walled  plain,  and  is  very  nearly  as  dark 
in  parts  as  Grimaldi  itself.  Just  to  the  south-east  of  these 
two  last-named  formations  lie  the  Lunar  Cordilleras  (274) 
and  the  D’Alembert  Mountains  (275).  What  is  probably  a 


42  HOURS  WITH  A THREE-INCH  TELESCOPE. 


portion  of  this  latter  chain  reappears  as  the  Rook  Moun- 
tains (276).  Rather  further  south  along  the  limb,  when  the 
moon  is  nearly  thirteen  days  old,  the  series  of  ring  plains, 
Lohrmann  (153),  Hevelius  (154),  and  Cavalerius  (155),  offers 
an  interesting  spectacle.  Hevelius  has  a convex  interior, 
but  by  no  means  so  regular  as  that  of  Mersenius,  nor  does 
the  convexity  fill  the  enclosed  area  in  the  same  way. 
Leaving  the  moon’s  limb  now  for  the  Ocean  of  Storms,  we 
arrive  at  the  most  brilliant  spot  on  the  whole  surface, 
Aristarchus  (148),  of  which  I have  spoken  before  (p.  22),  as 
conspicuous  on  the  dark  limb  when  the  moon  is  young.  I 


possible  to  reproduce  this  extraordinary  lustre  in  a wood- 
engraving ; it  is  actually  unp'easant  to  the  eye  even  in  a 
three-inch  telescope.  The  diameter  of  Aristarchus  is  twenty- 
eight  miles,  and  its  walls  are  terraced— albeit  the  ter- 
racing is  seen  with  considerable  difficulty,  owing  to  the 
glare.  It  has  a concave  interior  with  a central  moun- 
tain — if  possible  even  more  brilliant  than  the  internal 
walls  themselves.  Its  eastern  wall  extends  into  a table-land 
by  which  it  is  connected  with  Herodotus  (149).  This  last- 

1 The  student  is  recommended  to  pass  a pale  wash  of  Indian  ink 
over  the  interior  of  the  crater  Herodotus  (the  right-hand  one  in  the 
sketch  above),  as  the  engraver  has  mistakenly  made  it  of  the  same  tint 
as  the  surrounding  Mare. 


had  a curious  illustration  of  the 
extreme  brightness  of  this  forma- 
tion on  the  occasion  in  which  the 
accompanying  drawing  was  made 
(the  nieht  of  August  15,  1883). 


Fig.  22.-  Aristarchus  and  Hero- 
dotus. Moon’s  Age,  12*86  days. 1 


Huge,  black,  cumulus  clouds 
were  driving  at  intervals  across 
the  sky,  and  several  times  when 
the  moon  was  absolutely  blotted 
out  from  view  in  the  field  of  the 
telescope,  Aristarchus  continued 
to  shine  like  a small  ill-defined 
planet.  It  is  difficult  or  im- 


THE  MOON. 


43 


named  formation  is  less  than  24  miles  across,  and  is  very 
notably  darker  than  Aristarchus.  The  chief  object  of 
interest  in  connection  with  Herodotus  is  the  curious  ser- 
pentine valley  or  cleft  which  originates  in  it,  and  which  was 
well  seen  when  our  sketch  was  made.  Schmidt  asserts  that 
this  is  1,663  feet  deep  in  places.  It  enters  Herodotus  at  a 
point  concealed  by  shadow  at  the  epoch  of  our  drawing. 

With  this  will  terminate  our  description  of  the  moon’s 
surface.  I have  not  considered  it  necessary  to  make  more 
than  casual  reference  here  to  the  aspect  of  lunar  foimations 
after  full  moon,  inasmuch  as  it  differs  only  from  that  which 
they  present  before  full  moon  in  that,  while  in  the  latter 
case  the  sun  is  rising  on  them  and  their  shadows  are  cast  to 
the  east,  after  full  moon  the  sun  is  setting  to  them  and 
their  shadows  fall  towards  the  west.  Tigs.  8,  9,  and  10 
(p.  25)  will  sufficiently  illustrate  this.  As  I began  by  saying, 
I am  not  writing  a treatise  on  selenography,  and  my  object 
has  merely  been  to  invite  the  attention  of  the  beginner  to 
certain  typical  lunar  formations,  whkh  can  be  observed 
with  such  an  instrument  as  has  been  employed  for  the 
purpose  of  this  work.  Our  map  will  in  itself  supply  the 
student  with  ample  work  for  a considerable  period,  inasmuch 
as  it  will  enable  him  to  identify  four  hundred  of  the  prin- 
cipal formations  on  the  face  of  the  moon.  The  possessor 
of  a telescope  whom  I may  have  succeeded  in  interesting  in 
the  study  of  lunar  detail  will  probably  procure  Neison’s 
great  book  on  ‘The  Moon,’  a work  containing  more  detailed 
information  with  reference  to  selenography  proper  than  any 
one  extant  in  the  English  language. 


44  HOURS  WITH  A THREE-INCH  TELESCOPE. 


CHAPTER  IV. 

OCCULTATIONS  OF  STARS  AND  PLANETS  BY  THE  MOON. 

There  are  few  more  curious,  instructive,  nay,  even  startling 
sights  in  the  heavens  than  the  occultation  of  a fixed  star  (or 
more  rarely  of  a planet)  by  the  moon.  When  this  occurs 
at  the  dark  limb  of  our  satellite,  its  suddenness  is  such 
as  not  infrequently  to  extort  an  exclamation  from,  as  it 
invariably  causes  a start  by,  the  observer  who  witnesses  it 
for  the  first  time.  The  moon,  as  everybody  knows,  com- 
pletes a sidereal  revolution  round  the  earth  in  about  2 7 ’32 
days  ; in  other  words,  that  period  elapses  from  the  time  of 
her  quitting  any  given  star  to  her  return  to  it  again.  It  may 
be  worth  while  to  mention  incidentally  that  while  the  moon 
has  thus  been  travelling  in  an  easterly  direction  through  the 
sky,  the  sun  has  also  (apparently)  been  moving,  much  more 
slowly,  in  the  same  direction  ; so  that  if  we  assume  that  the 
sun  and  moon  are  in  conjunction  (the  ‘ new  moon  ’ of  the 
almanacs),  at  the  end  of  the  27-32  days  the  moon  will  not 
have  overtaken  him  ; in  fact,  she  will  have  to  go  on  for  2-21 
days  before  she  comes  up  with  him,  and  it  is  new  moon 
again.  It  is  this  period  of  29-53  days  which  forms  the 
lunar  or  synodical  (Greek,  SrVoSos,  a meeting)  month  of 
the  books  on  astronomy.  In  thus  describing  her  monthly 
path  over  the  celestial  vault,  it  is  quite  obvious  that  she 
must  pass  between  us  and  such  stars  as  lie  in  her  course  ; 
the  stars  being — for  our  present  purpose — at  an  infinite 
distance,  while  she  is  only  some  239,000  miles  from  us. 
Her  orbit  is,  however,  very  far  indeed  from  being  a fixed 


OCCULTA TIONS  OF  STARS  AND  PLANETS.  45 


circle  in  the  sky.  Its  mean  inclination  to  the  ecliptic  is 
about  5°  9'  ; but  its  nodes  (the  points  where  it  cuts  the 
ecliptic  or  plane  of  the  earth’s  orbit)  are  perpetually  shift- 
ing. The  moon’s  perigee,  or  nearest  point  to  the  earth, 
is  shifting  ; and,  in  fact,  to  put  it  shortly,  at  the  end  of  any 
month  the  moon  does  not  return  accurately  to  that  point 
of  the  sky  from  which  she  set  out.  Were  the  path  of  the 
moon  a definite  and  unalterable  one  in  the  heavens,  she 
would,  of  course,  occult  the  same  stars  over  and  over  agaim 
month  after  month.  As  a matter  of  fact,  she  only  does  this, 
and  that  but  approximately,  after  223  lunations — a period 
known  to  the  Chaldseans  of  old  as  the  Saros.  Very  well, 
then,  travelling  thus,  as  I have  said,  from  west  to  east,  her 
eastern  limb  is,  of  course,  the  leading  one,  or  that  which 
covers,  hides,  or  occults  the  objects  lying  in  her  path.  From 
new  moon  to  full  moon  this  limb  is  unilluminated,  and 
the  effect  of  the  extremely  sudden  extinction  of  a star  when 
the  dark  limb  hides  it  is,  as  I began  by  saying,  of  an  abso- 
lutely startling  character.  ‘ In  a moment,  in  the  twinkling 
of  an  eye,’  the  star  which  shone  as  a brilliant  point  in  the 
sky  is  blotted  out  ; and  its  place  seemingly  knows  it  no 
more,  until  it  reappears  from  behind  the  opposite  or  illumi- 
nated edge  of  the  moon.  After  full  moon,  of  course,  the 
eastern  limb  is  illuminated,  so  that  the  disappearance 
takes  place  at  the  bright  edge,  and  the  star  on  its  reappear- 
ance starts  instantaneously  from  behind  the  dark  limb.  A 
few  days  on  either  side  of  new  moon,  when  the  dark  limb 
is  visible  by  earthshine — or,  in  the  popular  form  of  expres- 
sion, we  can  see  the  old  moon  in  the  new  moon’s  arms — 
a new  charm  is  added  to  the  spectacle  of  an  occultation,  in- 
asmuch as  before  full  moon  the  faintly  lighted  dark  limb 
can  be  actually  seen  approaching  the  star  which  it  is  soon 
to  obliterate.  Now  it  fortunately  happens  that  occultations 
are  phenomena  peculiarly  within  the  range  and  capability  of 
a three-inch  telescope.  Moreover,  should  the  owner  of 
such  an  instrument  happen  to  possess  a trustworthy  chro- 
nometer or  regulator,  he  may  not  only  derive  great  personal 


46  HOURS  WITH  A THREE-INCH  TELESCOPE. 


pleasure  and  amusement  from  the  observation  of  the 
phenomena  of  which  I am  treating,  but  may  render  real 
and  enduring  service  to  science  by  the  publication  of  his 
observations  of  the  occultations  which  are  predicted  in  the 
‘ Nautical  Almanac.’  It  may  encourage  the  student  and 
young  observer  to  be  assured  that  observations  of  occulta- 
tions made  with  a three-inch  telescope  and  an  accurate 
chronometer,  may  be  of  real  service  in  correcting  the  lunar 
tables,  and  the  theory  generally.  As  an  illustration  of  the 
preceding  remarks,  I will  take  the  occultation  of  A.  Gemi- 

norum  by  the  moon, 
which  happened  on 
Thursday,  March  6, 
1884.  Our  sketch  re- 
presents the  aspect  of 
affairs  at  roh.  10m.  4s. 
p.m.,  at  the  instant  of 
the  star’s  disappear- 
ance at  the  moon’s 
dark  limb,  as  seen  in 
a three-inch  telescope 
armed  with  a Huy- 
ghenian  (inverting)  eye- 
piece magnifying  80 
diameters. 

The  reappearance 
happened  at  a point  in  the  bright  limb  which  may  be 
found  in  the  engraving  by  opening  the  legs  of  a pair  of 
compasses  o-55  in.,  and  placing  one  leg  on  the  lowest 
illuminated  point  of  the  moon’s  disc  ; then  will  the  other 
leg  cut  the  bright  limb  at  the  spot  at  which  it  took  place. 
It  occurred  about  nh.  12m.  9s.  p.m.  Let  us  now  turn  to 
p.  435'of  the  ‘ Nautical  Almanac  ’ for  that  year,  and  see  in 
what  form  this  phenomenon  is  there  predicted,  with  a view 
to  explaining  and  utilising  such  prediction  for  the  information 
and  instruction  of  the  student. 


Fig.  23.  — Occultation  of  a Geminorum  by 
the  Moon,  March  6,  1884,  power  80. 


OCCULTA  TIOMS  OF  STARS  AND  PLANETS. 


47 


OCCULTATIONS  VISIBLE  AT  GREENWICH. 


Month 

and 

Day 

Star’s  Name 

Magnitude 

Disappearance 

Reappearance 

Sidereal 
1 Time 

Mean 
• Time 

Angle  from 

Sidereal 

Time 

Mean 

Time 

Angle  from 

N. 

Point 

Vertex 

N. 

Point 

Vertex 

Mar.  6 

A Geminorum 

3- 

h.  m. 
9 10 

h.  m. 
10  10 

O 

107 

0 

134 

h.  m. 
10  11 

h.  m. 
11  11 

226 

0 

262 

***  The  angles  are  reckoned  towards  the  right  hand  round  the  circumference  of 
the  moon’s  image,  as  seen  in  an  inverting  telescope. 


The  first  column  gives  the  date  ; the  second,  the  star’s 
name  ; the  third,  its  magnitude  ; the  fourth,  the  sidereal 
time — or  that  shown  by  an  ordinary  observatory  clock — at 
which  the  disappearance  takes  place  ; and  the  fifth,  the 
corresponding  instant  of  mean  solar  time  at  which  the  star 
vanishes.  The  sixth  and  seventh  columns  require  more  de- 
tailed explanation.  The  ‘north  point’ of  the  table  is  that 
point  of  the  moon’s  limb 
cut  by  a circle  passing 
through  ■ the  north  pole 
and  the  moon’s  centre. 

It  is  in  real  truth  the 
south  point  of  the  lunar 
limb  ; but  it  is  uppermost 
in  the  field  of  view,  and 
is  known  technically  as 
the  N.  point.  From  this, 
angles  are  measured  right 
round  the  moon’s  circum- 
ference, in  the  direction 
in  which  the  hands  of  a watch  move.  Our  second  figure  will 
illustrate  this.  This  will  render  the  mode  of  measurement 
intelligible  at  a glance.  Here,  evidently,  o°  is  the  moon’s 
(technical)  N.  point,  and  the  measurement  of  angles  from  it  is 
indicated  by  the  figures.  Suppose,  for  example,  that  we  found 
from  the  tables  that  the  angle  from  N.  point  of  some  star  at 


o° 


Fig.  24. 


48  HOURS  WITH  A THREE-INCH  TELESCOPE. 


disappearance  was  6o°  ; then  should  we  know  that  it  would 
be  occulted  at  the  point  marked  a in  our  diagram.  Were 
the  angle  790,  it  would  disappear  at  b , 1160  at  e,  and  so  on. 
Were,  on  the  other  hand,  the  angle  of  reappearance  given 
as  245 0 from  N.  point,  d would  be  the  point  in  the  limb 
from  which  it  would  emerge,  as  would  e were  such  angle 
2920.  These  ‘angles  from  north  point’  are  employed 
with  telescopes  mounted  equatorially  (Chap  I.  p.  5).  When 
the  observer  has  only  an  altazimuth  mounting  {Joe.  cit.),  as 
is  usually  the  case  with  a three-inch  telescope,  the  angles 
must  be  measured  from  the  moon’s  vertex.  This,  in  effect, 
is  the  point  in  her  limb  at  the  top  (in  an  inverting  telescope) 
cut  by  a plumb-line  passing  through  her  centre.  I have  so 
far  spoken  as  though  the  disappearance  of  stars  was  in  all 
cases  instantaneous,  and  so,  as  far  as  my  own  experience 
goes,  it  is.  Other  observers,  though,  have  seen  the  very 
curious  phenomenon  of  the  apparent  projection  of  the  star 
on  to  the  (almost  invariably  bright)  limb  of  the  moon.  It 
is  a noteworthy  fact  that  this  curious  appearance  has  been 
practically  confined  to  red  stars,  like  Aldebaran  ; but  this 
goes  a very  little  way  in  helping  towards  a solution  of  so 
anomalous  an  effect.  The  occultations  of  planets  are 
comparatively  rare  phenomena,  and  should  be  sedulously 
watched  whenever  they  occur.  An  occultation  of  Venus 
occurred  about  three  o’clock  in  the  afternoon  on  February 
29,  1884  ; but  no  intimation  or  prediction  of  it  whatever  was 
given  in  the  1 Nautical  Almanac  ’ ! Occultations  of  Saturn 
and  Jupiter  afford  delightful  spectacles  to  the  observer  ; 
the  extreme  sharpness  of  their  superficial  detail,  where 
actually  in  contact  with  the  moon’s  limb,  entirely  negativing 
any  suspicion  of  a lunar  atmosphere.  Irrespectively  alto- 
gether, however,  of  the  mere  beauty  and  interest  of  the 
phenomena  of  lunar  occultations,  and  their  entire  suitability 
for  observation  with  our  instrumental  means,  I would,  in 
conclusion,  once  more  insist  on  their  scientific  value.  Made 
simultaneously  at  stations,  the  longitude  of  one  of  which  is 


OCCULTATIONS  OF  STARS  AND  PLANETS. 


49 


well  determined,  they  afford  excellent  (if  somewhat  operose) 
means  of  deducing  that  of  the  other.  Moreover,  as  I have 
before  said,  if  the  student  be  the  possessor  of  a chronometer 
indicating  accurate  Greenwich  mean  time,  he  may  by  his 
own  unaided  exertions  render  real  help  towards  the  improve- 
ment of  the  lunar  theory,  and  perchance  earn  a niche  in 
the  Temple  of  Fame  in  days  yet  to  come. 


F 


So  HOURS  WITH  A THREE-INCH  TELESCOPE. 


CHAPTER  Y. 

MERCURY. 

Mercury  in  a three-inch  telescope  is,  to  speak  as  euphe- 
mistically as  possible,  a rather  disappointing  object.  Nor  is 
the  reason  far  to  seek.  EYen  in  inferior  conjunction — when 
(save  during  the  rare  occasions  of  his  transit  over  the  sun's 
disc)  he  is,  of  course,  invisible — his  diameter  scarcely  ex- 
ceeds io";  while  at  the  times  of  his  greatest  elongation- 
east  or  west  of  the  sun,  as  the  case  may  be— his  little 
crescent  only  measures  some  7"  from  cusp  to  cusp.  Hence 
it  becomes  necessary  to  employ  as  high  a power  as  our 
telescope  will  bear  to  get  any  idea  of  the  planet’s  figure  and 
general  appearance  ; while  as  to  the  detail  alleged  in  astro- 
nomical works  to  have  been  seen  on  his  surface,  the  pos- 
sessor of  such  an  instrument  as  that  with  which  our  obser- 
vations are  made  must  be  content  to  walk  by  faith,  and  not 
by  sight.  The  explanation,  which  will  be  found  in  the  next 
chapter,  of  the  phases  exhibited  by  Venus  is  equally  appli- 
cable, mutatis  mutandis , to  those  shown  by  Mercury,  and 
the  reader  is  requested  to  turn  to  what  is  said  in  the  place 
cited,  for  the  better  apprehension  of  what  is  to  follow. 
Mercury  then  attained  his  greatest  elongation  west  of  the 
sun  at  7 p.m.  on  September  18,  1885,  and  hence,  at  the 
date  of  our  observation,  he  was  about  three  days  and  a halt 
from  it.  A glance  at  the  figure  will  show  that  the  illumi- 
nated portion  of  the  planet  visible  was  decidedly  smaller  than 
it  should  theoretically  have  been  frem  the  relative  positions 


MERCURY. 


5i 


of  the  Sun,  Earth,  and  Mercury.  As  may  be  imagined, 
however,  some  attention  is  needed  to  detect  this  feature  in 
so  tiny  a crescent  as  the  planet  presents.  The  shading 
towards  the  terminator,  or  ap- 
parent inner  edge  of  the  crescent, 
is  both  considerable  and  ill-de- 
fined. Whether  this  has  its  origin 
in  the  planet’s  atmosphere  or  not 
is  by  no  means  easy  to  determine. 

The  student,  after  scrutinising 
Mercury,  should  turn  his  tele- 
scope upon  Venus  (should  she 
be  conveniently  placed),  the 
brilliance  of  whose  light  stands' 
out  in  striking  contrast  to  the 
comparatively  feeble  illumination 
of  her  inner  neighbour.  Spots,  streaks,  &c.  (whence  a 
hypothetical  rotation  period  has  been  deduced),  and  a blunt- 
ing of  at  least  one  of  the  horns  of  the  crescentic  planet 
have  been  seen,  either  objectively  or  in  imagination,  by 
many  observers  ; but,  as  I have  hinted  above,  all  such  de- 
tail is  hopelessly  beyond  the  possessor  of  a small  instru- 
ment. 

As  in  the  case  of  Venus,  when  Mercury  is  in  or  near 
either  of  his  nodes  at  the  time  of  inferior  conjunction,  he 
passes  across  the  sun’s  disc — or,  as  it  is  technically  said, 

‘ transits  ’ the  sun  as  a black  spot.  With  too  light  an 
eye-shade  he  shows  well  the  notorious  ligament  or  black 
drop  (concerning  which  so  much  has  been  written  in  con- 
nection with  transits  of  Venus)  at  his  entry  on  and  exit 
from  the  sun’s  face.  An  aureola  or  luminous  ring  round 
the  black  disc  of  the  planet  has  also  been  seen  while  it  has 
been  crossing  the  sun  ; while  several  observers  of  skill  and 
repute  have  seen  one,  and  even  two,  whitish  spots  on  the 
dark  disc  of  the  planet  itself  under  the  same  conditions. 
These  phenomena  are  quite  within  the  reach  of  such  a 


Fig.  25. — Mercury,  Sept.  15,  1885. 
Power,  160. 


52  HOURS  WITH  A THREE-INCH  TELESCOPE. 


telescope  as  that  whose  use  I am  presupposing  ; but,  un- 
fortunately, the  student  will  have  to  wait  some  time  before 
attempting  to  verify  such  observations  as  those  which  I have 
just  described,  inasmuch  as  only  two  more  transits  of 
Mercury  will  occur  during  the  present  century  : the  first 
happening  on  May  9,  1891,  and  the  next  on  November  10, 
1894. 


CHAPTER  VI. 


VENUS. 

The  glorious  planet  we  are  now  going  to  examine  surpasses, 
under  certain  circumstances,  every  object  in  the  sky  in 
lustre  ; and  hence  the  poet,  in  saying  that — 

Hesperus  that  led 
The  starry  host  rode  brightest, 

simply  expressed  a bald  matter  of  scientific  fact.  About  a 
month  after  she  has  attained  what  is  called  her  greatest 
elongation  east,  or  the  same  time  before  she  acquires  her 
greatest  western  elongation,  she  may  be  detected  with  the 
naked  eye  in  the  sunlit  sky  ; and,  when  in  the  former  phase, 
casts  a very  perceptible  shadow  at  night  upon  any  white 
surface.  Her  great  brilliance  under  these  conditions  renders 
her  the  most  severe  test  of  the  achromatism  of  a telescope 
that  we  possess  ; and  an  instrument  must  be  perfect  indeed 
that  will  exhibit  an  absolutely  colourless  image  of  her  at 
this  time. 

In  order  that  the  beginner  may  have  an  intelligent  idea 
of  what  he  is  going  to  look  at,  it  will  be  necessary  to  recall 
a few  elementary  facts  in  connection  with  the  orbits  of  the 
Earth  and  Venus.  Everybody — at  least,  everybody  who 
will  read  these  lines — knows  that  Venus  goes  round  the  sun 
in  an  orbit  inside  our  own  ; in  other  words,  her  mean  dis- 
tance from  our  mighty  centre  of  light  and  heat  is  66|  mil- 
lions of  miles,  while  ours  is  92^  millions.  She  travels  through 
this  orbit  in  2247  days.  Now,  if  we  were  standing  still, 


54  HOURS  WITH  A THREE-INCH  TELESCOPE. 


she  would  go  through  all  her  phases  in  this  period  ; and  if 
she  were  in,  say,  inferior  conjunction  (i.e.,  in  a line  between 
the  Earth  and  the  sun)  on  any  given  day,  after  2247  days 
she  would  return  to  the  same  spot.  But  the  Earth  itself 
goes  round  the  sun  in  365 '26  days,  of  course  in  the  same 
direction  as  Venus,  so  that  what  is  called  her  synodic  period 
(Grek,  o-wo8o;,  a meeting),  or  time  elapsing  between  one 
meeting  with  the  Earth  and  the  next,  is  really  583-92  days. 
For  example,  Venus  was  in  inferior  conjunction  with  the 
sun  at  2 a.m.  on  July  12,  1884.  Her  next  inferior  conjunc- 
tion did  not  happen  until  7 p.m.  on  February  18,  1886. 
Now,  if  we  suppose  her  to  be  in  inferior  conjunction,  and 
also  in  or  near  one  of  the  nodes  of  her  orbit,  it  is  pretty 
evident  that  she  will  pass  across  the  face  of  the  sun  as 
viewed  from  the  Earth,  and  we  shall  have  a transit  of  Venus. 
With  th:s  phenomenon,  however,  we  have  but  small  concern 
here.  It  last  happened  on  December  6,  1882,  and  will  not 
recur  until  June  7,  2004,  when  the  hand  that  pens  these 
words  and  the  eyes  which  rest  upon  them  will  alike  be  dust 
and  ashes.  If,  though,  the  planet  is  far  from  her  node  at 
the  time  of  inferior  conjunction,  then  she  passes  above  or 
below  the  sun  as  seen  by  us.  On  July  12,  1884,  she  was 
nearly  50  south  of  the  sun’s  centre.  Under  these  circum- 
stances, as  we  shall  presently  see,  while  nearly  the  whole  of 
her  lighted  face  must  be  turned  towards  the  sun,  yet  an 
extremely  narrow  portion  of  her  illuminated  limb  is  percep- 
tible. As  she  travels  to  the  westward  of  the  sun  after  this 
as  a morning  star,  more  and  more  of  the  lighted  part  6f  her 
disc  becomes  visible  ; until  she  assumes  the  appearance  of 
the  moon  when  in  her  first  quarter;  or,  technically  speak- 
ing, is  ‘ dichotomised.’  As  will  be  seen  by  any  one  who 
will  draw  a diagram  or  plan  of  Venus’s  orbit,  her  diameter 
must  appear  the  largest  at  the  time  of  her  inferior  con- 
junction, and  must  diminish  just  as  her  illuminated  surface 
increases.  After  attaining  her  greatest  elongation  west  of 
the  sun  (which  can  never  exceed  470  15'),  the  planet  appears 
to  begin  to  move  back  again,  or  from  west  to  east,  grows 


VENUS. 


55 


smaller  and  smaller,  and  when  her  disc  is  becoming  fully 
illuminated,  disappears  behind  the  sun  in  the  glare  of  his 
light,  as  merely  a rather  big  star.  She  is  then  said  to  be  in 
superior  conjunction.  Emerging,  after  an  interval,  from 
his  rays  to  the  east  of  him,  she  becomes  an  evening  star, 
and  goes  through  all  her  phases  in  the  reverse  order,  increas- 
ing in  diameter  as  the  area  of  her  illuminated  surface  dimin- 
ishes.  Attaining  her  greatest  eastern  elongation,  and  then 
turning  back  as  a rapidly 
narrowing  crescent,  she 
finally  returns  to  inferior 
conjunction  again.  This  all 
being  understood,  we  will, 
at  last,  go  to  the  telescope. 

At  6 p.m.,  on  May  2, 

Venus  had  attained  her 
greatest  elongation  (450  27') 
east,  and  ei0ht  days  later 
the  accompanying  drawing 
was  made,  with  a power  of 
160,  in  a 3~tn.  telescope.  Fig.  26. — Venus,  May  10,  1884. 

Now  two  or  three  things  will  Power,  160. 

strike  the  observer  who  will  carefully  scrutinise  this  sketch. 
Perhaps  the  first  will  be  the  great  brilliance  of  the  illuminated 
limb  of  the  planet,  and  the  way  in  which  this  contrasts  with 
the  inner  portion  or  ‘terminator,’  shading  off  into  the  bright 
sky.  This  is  very  imperfectly  shown  in  the  engraving,  where 
the  inner  edge  is  represented  much  too  bright.  The  two  little 
cusps,  too,  so  sharp  and  bright,  will  certainly  catch  the  eye, 
from  the  want  of  correspondence  of  their  inner  edges  with  the 
interior  curve  of  the  planet’s  lighted  surface.  All  this  seems 
indicative  of  a dense  and  extensive  atmosphere  surrounding 
Venus.  One  effect  of  the  inner  shading  is  worthy  of  note, 
and  that  is  the  effect  it  has  in  reducing  the  area  of  the  planet 
which  should  be  theoretically  illuminated.  If  we  draw  a plan 
of  the  orbit  of  Venus,  we  shall  see  that  at  her  greatest  elonga- 
tion she  ought  geometrically  to  be  dichotomised,  i.e.,  exactly 


56  HOURS  WITH  A THREE-INCH  TELESCOPE. 


half  full ; but  it  will  be  seen  that  in  reality  she  is  rather  less 
than  this,  the  degradation  of  light  towards  the  terminator 
being  pretty  rapid.  Observers  of  repute  have  seen  the 
terminator  jagged  and  uneven,  like  that  of  the  moon  ; but  it 
is  too  much  to  expect  of  a three-inch  telescope  that  it  should 
exhibit  such  difficult  features  as  this.  A blunting  of  one  or 
both  of  the  horns  has  also  been  perceived  at  times  by  various 
astronomers,  both  in  this  country  and  on  the  Continent- 
And,  what  is  of  considerable  interest  to  the  possessors  of 
instruments  of  the  size  employed  for  the  purpose  of  these 
descriptions,  very  faint  dusky  spots  and  bright  patches  have 
been  perceived  from  time  to  time  in  telescopes  of  the  most 
varying  apertures  ; small  ones  showing  these  spots  as  well  as 
— in  fact,  better  than — some  of  the  larger  instruments.  This 
may  possibly  arise  from  the  general  glare  of  light  in  a large 
objective  or  mirror  deadening  the  eye  to  such  delicate 
details.  It  is  by  the  aid  of  these  spots,  real  or  imaginary, 
that  the  hypothetical  period  of  rotation  of  Venus  has  been 
determined. 

But,  however  beautiful  and  curious  the  spectacle  may  be 
which  is  presented  by  Venus  in  quadrature,  it  will  scarcely 
interest  the  student  so  much  as  his  first  view  of  her  in 
inferior  conjunction.  Our  succeeding  figure  exhibits  the 
planet  as  seen  in  the  same  instrument  and  with  the  same 
power  as  that  employed  to  make  our  first  sketch  with.  The 
contrast  between  these  two  aspects  of  Venus  will  arrest  the 
attention  at  once.  The  comparatively  small  half-moon  has 
become  converted  into  a hair-like  glittering  semicircle  of 
light,  enclosing  something  which  is  certainly  darker  than 
the  surrounding  sky.  The  very  abnormally  hazy  condition 
of  the  atmosphere  which  had  persisted  for  many  months  was 
against  the  perception  of  any  very  delicate  gradations  of 
shade,  so  that  the  whole  of  the  dark  body  of  Venus  was 
invisible  ; but  the  effect,  difficult  or  impossible  to  reproduce 
in  a wood-cut,  was  that  of  a disc,  dark  where  embraced  by 
the  crescent  of  light,  and  fading  into  the  light  of  the  sky 
outside  or  beyond  the  cusps.  On  the  occasion  of  former 


VENUS. 


57 


inferior  conjunctions,  the  whole  of  the  planet’s  dark  limb 
has  been  unmistakably  perceived.  In  order  that  it  may  be 
seen  to  the  greatest  advantage,  a very  small  diaphragm 
should  take  the  place  of  the  ordinary  one  between  the  two 
lenses  of  the  Huyghenian  eye-piece.  A blackened  card 
disc  with  a fine  hole  made  centrally  in  it  with  a red-hot 
needle  answers  capitally.  The  hot  needle  burns  the  fringed 
edge  of  the  perforation  and  leaves  it  clean  and  sharp.  The 
smaller  the  hole,  consistently  with  distinct  vision,  and  the 
more  sky  light  that  is  cut  off,  the  sharper  and  better  will 


Fig.  27. — Venus  in  Inferior  Conjunction,  July  it,  1884.  Power,  160. 

the  body  of  the  planet  appear.  This  little  device  will 
always  be  found  useful  when  any  body  is  to  be  viewed  in 
bright  sunlight. 

There  is  a queer  story — or,  perhaps,  it  would  be  more 
correct  to  say  a series  of  queer  stories — with  reference  to 
various  observations  of  a satellite  or  companion  to  Venus, 
situated  always  close  to  the  planet,  sometimes  on  one  side 
of  her,  sometimes  on  the  other,  but  always  exhibiting  a 
phase  identical  with  hers.  The  most  feasible  explanation  of 
this  is  that  it  has  had  its  origin  in  each  case  in  what  is  called 


58  HOURS  WITH  A THREE-INCH  TELESCOPE. 

‘ a ghost’  in  the  eye-piece,  i.e.  in  a reflection  of  the  planet's 
image  from  the  convex  surface  of  the  eye-lens  on  to  the 
plane  surface  of  the  field-lens,  and  so  back  to  the  eye  of  the 
observer.  An  observation  made  by  Short,  the  famous  op- 
tician, in  1740,  who  did  use  two  different  telescopes,  seems 
the  only  one  to  throw  any  legitimate  doubt  upon  this  ex- 
planation. M.  Houzeau,  the  eminent  Belgian  astronomer, 
however,  is  so  convinced  of  the  objective  reality  of  the 
various  apparitions  of  this  satellite,  that  in  del  et  Terre  for 
May  15,  1884,  he  gravely  propounds  the  hypothesis  that  a 
little  planet  (which  he  provisionally  names  Neith)  revolves 
round  the  sun  in  an  orbit  just  exterior  to  that  of  Venus  her- 
self. Here  there  is  an  opportunity  for  the  student  to  dis- 
tinguish himself.  He  has  only  to  watch  Venus  day  and 
night,  until  he  picks  up  this  attendant,  to  do  so.  Whether, 
though,  he  succeeds  or  whether  he  fails  in  this  attempt,  he 
will  find  himself  amply  repaid  for  any  amount  of  labour  by 
the  diversified  but  always  beautiful  appearance  of  the  planet 
as  she  speeds  on  her  path  round  the  sun,  and  may  find 
infinitely  less  profitable  ways  of  spending  his  time  than  by 
the  devotion  of  a daily  half-hour  to  watching  Venus  in  a 
three-inch  telescope. 


59 


CHAPTER  VII. 

MARS. 


The  study  of  Areography  (Greek  VA pys,  Mars),  or  minute 
Martial  detail,  can  only  be  properly  carried  on  by  the  aid  of  a 
telescope  of  considerable  size  and  power.  Notwithstanding 
this,  we  shall  find  that  a good  deal  that  is  curious  and  instruc- 
tive in  connection  with  the  physical  structure  of  this  planet  is 
well  within  the  capabilities  of  the  instrument  we  are  using ; 
and  I propose  in  this  chapter  to  examine  such  features  of 
his  surface  as  are  susceptible  of  exhibition  with  only  three 
inches  of  aperture.  A haze  of  cirro-strati  is  drifting  over 
the  sky  as  I turn  my  telescope  on  to  Mars ; but  this 
really  has  the  effect  of  subduing 
the  general  glare  of  the  planet, 
sharpening  such  detail  as  is  per- 
ceptible, and  improving  definition 
generally.  Compared  with  the 
mighty  orb  of  Jupiter,  Mars  pre- 
sents such  a small  disc  that  we  find 
it  necessary  rather  to  overpress 
magnifying  power  than  otherwise, 
to  see  fairly  the  principal  markings 
he  exhibits.  We  arm  then  our 
instrument  with  a power  of  204,  and,  on  directing  it  to 
the  planet,  behold  the  spectacle  depicted  in  the  above 
engraving. 

Unlike  Jupiter  and  Saturn,  the  disc  of  Mars — in  its  pre- 
sent phase — appears  circular.  When  Mars  is  in  so-called 


Fig.  28.— Mars,  Feb.  18,  1884, 
gh.  35m.  G.M.T.  Power,  204. 


60  HOURS  WITH  A THREE-INCH  TELESCOPE. 


‘quadrature’  with  the  sun,  he  will  be  very  perceptibly 
gibbous  (fig.  36,  p.  81),  but  under  no  circumstances  has  any 
trustworthy  measurement  shown  a sensible  excess  of  his 
equatorial  over  his  polar  diameter.  Dawes  found  the 
ellipticity  absolutely  imperceptible.  Regarding  then  this 
circular  disc,  what  do  we  see  ? A bright  white  patch  at  the 
bottom — or  north  pole — of  the  planet  is  probably  the  first 
thing  that  will  arrest  the  attention  of  the  observer,  contrast- 
ing as  it  does  markedly  with  the  general  orange  tint  of  the 
planet.  Bounded  on  one  side  by  the  limb,  this  brilliant 
marking  exhibits  the  form  of  a double  convex  lens.  It  is 
entirely  surrounded  on  its  southern,  or  upper  edge,  by  a 
greenish-grey  dark  marking,  from  which  rises  another  of  a 
shape  akin  to  that  of  the  old-fashioned  champagne -glass  of 
the  days  of  our  fathers  and  grandfathers.  Instead,  however, 
of  terminating  in  a symmetrical  rim,  the  southern  extremity 
of  this  bifurcates  in  a fashion  which  somewhat  suggests  the 
spreading  of  the  wings  of  a sea-gull.  The  central  southern 
portion  of  this  is  the  darkest  part  of  it.  Our  sketch  was 
made,  as  stated  above,  at  9h.  35m.  at  night.  Had  I de- 
ferred it  until  four  o’clock  the  next  morning,  the  planet 
would  have  presented  a very  different  aspect  indeed;  for 
Mars  rotates  on  his  axis  in  24I1.  37m.  22-7355.  (thus  taking 
a little  more  than  half  an  hour  longer  than  the  Earth  to 
complete  one  rotation),  and  from  this  cause,  of  course, 
fresh  portions  of  his  surface  are  presented  to  our  view  as 
the  night  advances,  just  as  in  the  case  of  Jupiter.  There  is, 
however,  this  very  notable  difference  between  the  markings 
on  the  two  planets,  that  whereas,  as  stated  on  p.  67,  the 
detail  on  Jupiter  is  in  no  legitimate  sense  permanent, 
existing  as  it  probably  does  in  a vaporous  and  very  mobile 
envelope  of  enormous  extent,  in  Mars  the  markings  are 
persistent,  and  certainly  form  parts  of  his  actual  solid  (and 
liquid)  surface ; so  that  maps  of  no  inconsiderable  accuracy- 
have  been  formed  of  them.  What,  then,  do  they  signify  ? 
It  seems  in  a high  degree  probable  that,  in  looking  at  Mars, 
we  are  regarding  a miniature  of  our  own  woild.  That  the 


MARS. 


61 


general  surface  of  the  planet  may  well  represent  land  of  a 
geological  structure  allied  to  the  ‘ Triassic,’  or  New  Red 
Sandstone  rocks  so  well  displayed  at  Exmouth,  Dawlish, 
and  Teignmouth  in  this  country;  that  the  darker  markings 
are  nothing  but  oceans,  seas,  straits,  and  lakes  ; while  the  con- 
spicuous white  patch  at  the  pole  has  its  origin  in  the  exist- 
ence there  of  the  huge  tracts  of  glacier  and  snow-covered 
land  and  ice-locked  sea  of  the  Martial  arctic  regions.  For, 
during  the  present  opposition  of  Mars,  the  north  pole  of  the 
planet  is  turned  towards  the  earth,  and  it  will  be  seen,  from 
the  position  of  the  planet’s  axis  with  reference  to  us,  that  his 
south  pole  is  wholly  hidden,  from  being  on  the  other  side  of 
him.  The  reason  for  this  is  worthy  of  a brief  examination. 
Mars  goes  round  the  sun  in  686-98  days,  the  Earth  de- 
scribing her  orbit  in  365-26  days;  so  that,  being  in  opposi- 
tion at  any  given  date,  an  interval  of  779-84  days  must 
elapse  ere  they  return  to  it.  At  least,  this  is  the  mean 
period  between  two  successive  oppositions;  but,  owing  to 
the  great  eccentricity  of  Mars’  orbit,  this  varies  as  opposi- 
tions occur  near  his  perihelion  or  aphelion  (points  of  his 
nearest  approach  to  and  greatest  recession  from  the  sun)  re- 
spectively. Moreover,  the  equator  of  Mars  is  inclined  some 
2 70  to  the  plane  of  his  orbit.  As  the  inclination  of  our  own 
equator  is  only  23^°  to  the  ecliptic,  it  is  evident  that  the 
vicissitudes  of  the  Martial  seasons  must  be  more  aggravated 
than  in  our  own  case.  But  we  have  spoken  of  this  tilt  of 
the  planet’s  axis  mainly  for  the  purpose  of  pointing  out  that 
while  at  certain  oppositions  the  north  pole  of  the  planet  must 
be  turned  towards  us,  at  others  we  must  see  his  south  pole  ; 
while  at  intermediate  points — answering  to  our  terrestrial 
equinoxes — we  must  see  both  poles,  just  as  in  the  circular 
maps  of  the  earth  which  form  the  frontispieces  to  so  many 
books  on  geography.  The  south  pole  of  the  planet,  as  I have 
said  above,  is  wholly  invisible  now ; but,  during  the  memo- 
rable opposition  of  1877,  a great  white  lenticular-shaped 
patch  on  the  southern  limb  of  Mars  formed  just  as  con- 
spicuous a feature  as  the  corresponding  north  polar  one 


62  HOURS  IVITH  A THREE-INCH  TELESCOPE. 


(then  invisible)  does  now.  From  all  this  it  will  be  evident 
that  to  get  a true  idea  of  Areographical  detail,  we  must 
watch,  and  carefully  draw,  Mars  during  several  oppositions. 
It  is  very  remarkable  to  note  what  a curious  change  in  the 
aspect  of  any  given  feature,  far  north  or  south  of  the  equator 
of  Mars,  is  produced  by  foreshortening.  Nothing  but  long- 
continued  observation  and  abiding  faith  in  the  irrefragable 
principles  of  perspective  will  enable  the  student  to  identify  a 
given  spot  or  marking  when  viewed  under  so  very  different  an 
aspect.  The  best  popular  map  extant  of  the  leading  Mar- 
tial details  is  the  one  given  by  Prebendary  Webb  on  p.  146 
of  his  altogether  admirable  book,  ‘ Celestial  Objects  for 
Common  Telescopes.’  It  is,  however,  drawn  on  Mercator’s 
projection,  with  its  grossly  exaggerated  polar  dimensions  : 
and  the  young  observer  must  make  allowance  for  this  in 
using  it  for  regions  removed  by  any  considerable  distance 
from  the  equator.  The  great  inverted  conical  marking 
shown  in  our  sketch  (p.  59)  is  chiefly  composed  of  the 
Kaiser  Sea.  The  thin  arm  stretching  out  to  the  left  is  a 
part  of  Flammarion  Sea  ; that  to  the  right  a portion  of  the 
Dawes  Ocean.  The  Delambre  Sea  (confused  by  fore- 
shortening with  Nasmyth  Inlet  to  the  right)  forms  the  dark 
marking  surrounding  the  snow-cap  at  the  north  pole  (bottom) 
of  the  planet.  Situated  some  150°  in  longitude  from  the 
Kaiser  Sea  is  a very  notable  marking  in  the  southern  hemi- 
sphere of  Mars — unfortunately  in  an  unfavourable  position 
for  the  observer  just  now — which  is  called  Terby  Sea,  and 
which,  surrounded  by  Kepler  Land,  presents  a somewhat 
ludicrous  resemblance  to  an  eye.  In  the  absence,  however, 
of  a map,  detailed  descriptions  of  particular  markings  be- 
come merely  nugatory. 

It  only  remains  in  conclusion  to  mention  a few  facts  in 
connection  with  the  general  aspect  of  the  planet.  I have 
spoken  of  the  very  conspicuous  white  patches  at  or  near  the 
poles  of  Mars — patches  occasionally  so  brilliant  that  irradia- 
tion causes  them  to  appear  as  positively  projecting  slightly 


MARS. 


63 


beyond  the  outline  of  his  limb.  That  these,  as  I have  pre- 
viously intimated,  consist  of  ice  or  snow,  or  both,  the 
evidence  afforded  by  the  spectroscope  seems  to  render 
practically  certain,  showing  as  it  does  the  presence  of  large 
quantities  of  aqueous  vapour  in  the  Martial  atmosphere. 
There  is,  however,  a somewhat  similar  appearance,  which  I 
have,  among  others,  myself  observed,  that  of  lenticular-shaped 
white  markings  round  the  limb,  which  are  by  no  means  so 
easily  explicable.  A very  little  attention  will  show  the 
observer  with  the  telescope  that  the  ruddy  tint  of  the 
planet’s  face  is  most  marked  towards  the  centre  of  the  disc, 
and  that  the  limb  is  notably  paler  (occasionally  so  much  so 
as  to  seem  nearly  white,  as  was  the  case  in  the  autumn  of 
1879);  but  the  markings  of  which  I am  now  speaking  are 
large  white  patches  in  the  eastern  and  western  limbs  of 
Mars,  for  which  it  is  anything  but  easy  to  account,  though 
they  are  probably  atmospheric.  An  extremely  ingenious 
explanation  of  the  general  brightness  of  the  limb  will  be 
found  on  page  65  of  the  ‘ Essays  on  Astronomy,’  by  Mr. 
R.  A.  Proctor.  Mars  has  been  described  as  a miniature 
of  our  own  earth  ; and  undoubtedly  he  does  present  fea- 
tures connecting  his  physical  structure  more  closely  with 
ours  than  any  other  planet ; but  still,  irrespectively  of 
size,  there  are  differences  which  cannot  fail  to  strike  the 
thoughtful  observer.  The  most  salient  of  these  is  the 
difference  of  distribution  of  land  and  water.  On  the  earth 
only  about  51,500,000  square  miles  consist  of  dry  land, 
while  145,500,000  square  miles  are  covered  by  water.  On 
Mars  the  land  so  far  preponderates  that  the  largest  oceans, 
or  rather  seas,  can  only  be  described  as  more  or  less  land- 
locked. Schiaparelli  claims  to  have  discovered  a strange 
network  of  ‘ canals,’  uniting  various  portions  of  the  seas  of 
the  planet  hitherto  considered  to  be  isolated  ; but,  admitting 
for  argument’s  sake  the  objective  reality  of  these  features, 
they  are  hopelessly  beyond  the  optical  powrer  we  are  em- 
ploying. I may  mention,  in  conclusion,  that  a curious 


64  HOURS  WITH  A THREE-INCH  TELESCOPE. 

collateral  indication  of  the  existence  of  clouds,  or  vapour  in 
some  form,  has  been  observed  in  the  shape  of  the  dimming 
or  partial  obscuration  of  spots  and  markings  on  the  surface 
of  Mars ; while  others,  at  no  great  distance,  have  simulta 
neously  retained  all  their  usual  sharpness  and  comparative 
precision  of  outline. 


65 


CHAPTER  VIII. 

JUPITER. 

There  is  assuredly  no  member  ot  the  planetary  system 
which  offers  so  diversified  a series  of  phenomena  to  the 
contemplation  of  the  student  as  the  noble  one  which  I 
propose  to  examine  to-night.  Exceeding  the  earth  in 
volume  between  thirteen  and  fourteen  hundred  times,  and 
reflecting  (as  has  been  calculated)  some  sixty-three  out  of 
every  hundred  parts  of  the  sun’s  light  that  falls  upon  him, 
Jupiter  exhibits  a disc  and  shines  with  a lustre  which  renders 
him  a conspicuous  object  in  the  smallest  telescope.  Now 
it  might  be  supposed,  from  the  brightness  of  the  planet, 
that  a high  magnifying  power  would  be  most  applicable  to 
his  examination  ; as  a matter  of  fact  and  practice,  however, 
it  is  found  that  he  will  not  bear  so  much  amplification  with 
advantage  as  his  much  duller  neighbour  Saturn.  Moreover, 
all  the  curious  detail  of  which  I am  immediately  about  to 
speak  is  much  better  seen  when  a slight  haze  overspreads 
the  sky  and  softens  the  glare  of  light  cn  Jupiter’s  disc, 
which,  in  itself,  forms  an  impediment  to  the  perception  of 
very  delicate  markings.  Happily  for  us,  such  a haze  does 
cover  part  of  the  sky  on  the  night  which  I select  for  our 
drawing.  Wishing  to  use  as  much  magnifying  power  as  I 
can  without  impairing  definition,  I,  as  a limit,  fix  on  50  to 
each  inch  of  aperture  of  our  telescope.  Arming  it,  then, 
with  a power  of  150,  I turn  it  on  to  the  planet,  to  behold 
the  spectacle  of  which  the  engraving  (p.  66)  gives  a pretty 
accurate  idea. 


F 


66  HOURS  WITH  A THREE-INCH  TELESCOPE. 

The  first  thing  that  will  probably  arrest  the  attention  of 
the  young  observer  is  the  shape  of  the  planet.  Instead  of 
presenting  a circular  disc  it  will  be  seen  to  be  very  notably 
elliptical ; in  other  words,  flattened  at  the  poles,  and  bulging 
out  at  the  equator.  And  next,  as  the  eye  gets  accustomed 
to  the  image,  a series  of  belts  of  different  depths  of  shading 
and  even  of  markedly  different  colours  will  be  seen,  striping 
Jupiter’s  face  in  a direction  parallel  to  his  equator.  Let  us 


Fig.  29.— Jupiter.  Jan.  24,  1S84,  c)h.  5m.  p.m.  Power,  150. 


take  those  visible  when  our  drawing  was  made.  I will  begin 
at  the  top  of  the  planet,  which,  as  all  astronomical  telescopes 
invert,  is,  of  course,  its  south  pole.  For  some  little  distance 
the  tint  is  pretty  uniform— or  as  an  artist  would  say,  ‘flat 
but  then  it  is  seen  to  consist  of  a series  of  stripings ; the 
lighter  divisions  between  them  being  well  marked  and  easily 
visible  as  we  approach  the  northern  edge  of  this  polar  cap- 
ping. Then  comes  a distinct  white  streak,  bounded  on  the 
north  by  the  principal  belt  in  Jupiter’s  disc.  This  is  the 


run  ter. 


67 


most  conspicuous  feature  on  the  whole  face  of  the  plane*. 
It  is  of  a decidedly  brownish  tint,  and  its  northern  edge 
shows  a marked  tendency  to  throw  out  small  projections, 
so  as  to  give  a kind  of  ‘ scalloped  ’ effect.  With  a larger 
instrument  the  dark  matter  of  this  belt  is  seen  to  emit  pro- 
longations or  streamers  of  a wispy  character  from  these 
projections  diagonally  across  the  broad  bright  equatorial 
interval ; but  what  I have  drawn  (p.  66)  shows  everything 
that  it  is  within  the  power  of  a three-inch  telescope  to  reveal. 
The  northern  and  fainter  of  the  two  equatorial  dark  belts  is 
in  its  turn  succeeded  by  yet  another  white  streak ; that  by  a 
fainter  dark  one  still,  while  a multiplicity  of  stripes  covers 
the  north  pole  of  the  planet  with  a shading  which,  like  the 
south  polar  capping,  looks  practically  ‘ flat  ’ or  homogeneous. 
A little  attention  will  show  that  the  east  and  west  ‘ limbs  ’ 
(or  edges)  of  the  disc  are  not  quite  so  bright  as  its  central 
parts,  and  that  a slight  fading  away  of  the  belts  is  per- 
ceptible as  they  approach  the  limb.  The  satellite  and  its 
shadow  visible  on  the  left-hand  western  (or  ‘ preceding  ’ ) 
limb  of  the  planet  will  be  dealt  with  by-and-by.  It  must 
not,  however,  be  supposed  that  the  markings  I have  de- 
scribed are  constant  or  permanent,  like  the  oceans,  seas, 
continents,  and  islands  of  our  own  earth  ; or  that  a map 
of  Jupiter  constructed  from  observations  now  would  be  of 
much  use  in,  say,  1889.  Moreover,  confining  ourselves  to 
a single  night’s  observation,  the  details  on  the  surface  of 
the  planet  will  be  seen  to  undergo  a very  marked  change 
in  the  course  of  four  or  five  hours’  persistent  watching  of 
them  ; for  the  simple  reason  that  Jupiter  is  rotating  on  his 
axis  at  a speed  so  tremendous  as  to  be  beyond  our  power 
of  realisation.  The  notable  markings  which  appear  from 
time  to  time  upon  his  face  give  obvious  indications  of 
proper  motions  or  driftings  of  their  own,  and  this  compli- 
cates and  renders  uncertain  the  exact  determination  of  the 
period  of  the  planet’s  rotation.  It  would,  however,  seem 
that  he  turns  on  his  axis  in  a period  not  differing  greatly 
from  9h.  56m.,  so  that  a spot  on  his  equator  must  travel 


6S  HOURS  WITH  A THREE-INCH  TELESCOPE. 


at  the  rate  of  over  seven  miles  a second  ! A simple  plumb- 
line  must  form  an  effective  transit  instrument  in  such  a 
favoured  locality  ! Well,  then,  by  his  mere  rotation  fresh 
features  are  brought  into  view  ; but  after  the  lapse  of  nine 
or  ten  hours  we  shall  revert  to  that  aspect  of  the  planet 
which  it  presented  when  we  commenced  our  watch.  These 
changes,  therefore,  are  simply  such  as  arise  from  viewing  in 
succession  the  markings  extending  over  the  whole  of  J upper’s 
spheroidal  surface  — of  which,  of  course,  only  one  half  is 
visible  at  any  one  given  instant.  I have  now  to  speak  of 
the  much  more  remarkable  changes  which  occur  in  the 
markings  themselves  in  the  course  of  months  or  years.  As 
a familiar  example,  I may  refer  to  the  wonderful  great,  oval, 
red  spot  which  appeared  on  the  face  of  the  planet  to  the 
south  of  the  southern  one  of  his  equatorial  belts  in  the  year 
1879,  and  which  persisted  in  a perfectly  visible  form  up  to 
1883  ; although  it  has  now  entirely  vanished  in  a three-inch 
telescope.  In  August,  1878,  a great  circular  white  spot 
formed  a most  conspicuous  object  on  the  planet’s  equator, 
and  in  the  succeeding  year  one  enormous  dark  belt,  covering 
Jupiter’s  equatorial  regions,  was  broken  up,  or  perforated, 
as  it  were,  with  similar  but  more  irregularly  shaped  white 
markings.  In  1880,  a sinuous  continuous  white  marking 
separated  the  equatorial  belt  into  two — the  red  spot  at  this 
time  appearing  of  a pale  scarlet  tint.  In  1881,  the  red  spot 
persisting,  the  belts  became  much  narrower,  and  the  ‘van- 
dyking  ’ or  ‘ scalloping  ’ of  the  northern  edge  of  a dark  one 
south  of  the  equator  was  even  more  marked  than  the  similar 
phenomenon  in  the  somewhat  corresponding  dark  stieak 
shown  in  our  sketch  above.  And  so  I might  go  on  detailing 
a series  of  most  curious  changes  which  have  occurred  during 
the  last  five-and-twenty  years,  but  for  the  fact  that  my 
object  is  the  practical  one  of  teaching  the  student  exactly 
what  to  look  for,  rather  than  merely  the  giving  a list  of 
other  people’s  observations.  With  one  concluding  remark 
then,  on  the  phenomena  of  Tupiter’s  disc  proper.  I will 
pass  to  the  consideration  of  those  of  his  satellites.  It  is 


JUPITER. 


69 


this.  Jupiter  is  much  too  far  off  to  exhibit  phases  ; but  he 
does  show  an  indication  of  doing  so  when  what  is  technically 
called  in  quadrature,  or  when  he  is  90°  east  or  west  of  the 
sun,  as  measured  along  the  ecliptic.  Under  these  circum- 
stances the  limb  farthest  from  the  sun  exhibits  a perceptible 
shading,  much  too  deep  to  be  confused  with  the  slight 
fading  away  of  light  all  round  the  limb  which  is  always 
visible. 

Beautiful  and  remarkable  as  are  the  unstable  details 
which  diversify  Jupiter’s  face,  they  are,  in  one  sense,  almost 
monotonous  as  compared  with  the  perpetually  changing 
phenomena  of  the  four  moons  which  circle  round  him.  Of 
these  satellites  the  first,  second,  and  fourth  appear  as  sta^s 
of  the  seventh  magnitude,  and  the  third  as  a sixth  magni- 
tude star.  When  a satellite  crosses  Jupiter’s  face,  it  is  said 
to  1 transit  ’ him  ; its  entry  on  to  his  disc  being  ca'led  its 
ingress,  and  the  instant  of  its  leaving  his  opposite  limb  its 
egress.  When  it  passes  actually  behind  the  planet  it  is  said 
to  be  ‘ occulted  ; ’ and  when  it  plunges  into  his  shadow,  to 
be  ‘ eclipsed.’  I am  unwilling  to  introduce  anything  into 
this  volume  not  strictly  within  the  scope  embraced  by  its 
title  ; but  in  order  to  render  what  I am  about  to  describe 
intelligible,  it  will  be  necessary  to  enter  into  certain  elemen- 
tary explanations  of  the  conditions  under  which  we  view 
Jovian  phenomena  from  our  terrestrial  standpoint.  Leaving, 
then,  our  telescope  for  a few  minutes,  let  S in  our  figure  be 
the  sun,  E !>,  E0,  E a,  the  earth  travelling  round  him  in  the 
direction  of  the  curved  arrow  ; J,  Jupiter,  also  going  round 
the  sun  in  the  same  direction,  but  so  much  more  slowly  that 
— for  our  present  purpose — we  may  regard  him  as  standing 
still.  Then,  evidently,  Jupiter  will  cast  the  conical  shadow 
JUJ'  out  behind  him  into  space.  Let  us  call  D,  R,  STz, 
STV,  the  orbit  of  one  of  his  outer  satellites,  and  conceive 
it  to  coincide  with  the  plane  of  the  ecliptic.  From  E b draw 
the  lines  E/;J,  E b\  meeting  the  path  of  the  satellite  at  I 
and  E'.  Now,  imagine  the  earth  at  E/>,  i.e.,  before  Jupiter 
comes  into  opposition  (say  about  the  end  of  November 


70  HOURS  wn II  A THREE-INCH  TELESCORE. 


Fig.  30. 


1883).  Then,  when  a satellite  is  at  the  point  I in  its  orbit 
on  the  line  E/>J',  it  is  seen  to  enter  on  to  Jupiter’s  eastern 
limb,  and,  when  it  arrives  at  E',  to  leave  his  western  limb. 
This,  then,  is  a transit  of  the  satellite.  A glance  at  the 
figure  will  show  that  (independently  altogether  of  the  earth’s 
position)  when  this  same  satellite  passes  between  the  points 
ST/ and  ST'c  its  shadow  must  be  projected  on  to  Jupiter’s 
face,  just  as  the  shadow  of  our  own  moon  is  projected  on 
the  earth  in  an  eclipse  of  the  sun,  and  it  is  seen  to  cross  the 
planet  as  a round  black  spot.  Furthermore,  when  the 
satellite  plunges  into  the  planet’s  shadow  at  D,  it  disappears 
in  eclipse,  to  reappear  (under  the  conditions  we  are  suppos- 
ing) at  R.  It  will,  however,  be  noted  that  this  reappearance 
from  eclipse  is  only  to  be  followed  by  occultation  behind 
the  body  of  Jupiter  when  the  satellite  reaches  O,  the  satellite 
finally  reappearing  at  Jupiter’s  opposite  limb  when  it  reaches 
O'.  What  I have  said,  be  it  remarked,  applies  only  in  its 
entirety  to  the  two  outer  satellites.  The  inner  ones,  which 
describe  smaller  circles  round  the  planet,  disappear  in 
eclipse,  to  reappear  from  occultation , as  they  emerge  from 
the  actual  shadow  behind  the  body  of  the  planet.  It  will 
be  further  remarked  that  while  the  shadow  of  the  satellite 
enters  on  to  Jupiter’s  face  when  the  satellite  reaches  the 
point  ST/,  the  satellite  itself  does  not  follow  it  on  to  the 
limb  of  the  planet,  to  a terrestrial  observer,  until  it  arrives 
at  the  point  I in  its  orbit.  Thus,  to  sum  up,  before  opposi- 
tion the  shadows  precede  the  satellite  casting  them  in  their 
transits  ; the  inner  satellites  suffer  eclipse  and  reappear 
from  occultation,  and  the  outer  satellites  may  both  disap- 
pear and  reappear  from  eclipse  on  the  western  side  of  the 
planet,  to  be  subsequently  occulted  by  it.  When  Jupiter  is 
actually  in  opposition  (E0  in  our  figure),  evidently  the  satel- 
lites will  be  actually  superposed  on  their  shadows  as  they 
cross  the  disc  of  the  planet;  and,  as  the  whole  of  the  shadow 
cone  is  hidden  behind  him,  occultations  only,  and  no  eclipses, 
can  take  place.  After  opposition  (a  condition  of  things 
represented  at  E a above),  the  sequence  of  phenomena  is 


72  HOURS  WITH  A THREE-INCH  TELESCOPE. 


obviously  reversed  : the  satelliies  precede  their  shadows  over 
Jupiter’s  face  ; the  inner  satellites  are  occulted  by  the  planet 
and  reappear  from  eclipse  : and  the  outer  satellites  may 
disappear  in,  and  reappear  from,  occultation  to  be  subse- 
quently eclipsed.  The  student  will  now  be  prepared  to 
understand  that  when  our  sketch  of  Jupiter  was  made  cn 
the  night  of  Jan.  24,  1884,  the  planet  having  passed  oppo- 
sition a few  days  previously,  Satellite  I.,  which  was  about  to 
leave  his  disc,  after  crossing  it  in  transit,  was  slightly  in 
advance  of  its  shadow.  In  fact,  the  shadow  did  not  leave 


Fig.  31.— Eclipses  of  Jupiter’s  Satellites  (Dec.  1883). 


Fig.  3?. — Eclipses  of  Jupiter’s  Satellites  (Feb.  188.4). 


his  limb  for  seven  minutes  after  the  satellite  had  quitted  it. 
Near  quadrature  an  outer  satellite  may  have  left  the  planet's 
face  for  an  hour  or  two  before  its  shadow  even  enters  on  to 
it ! The  annexed  two  small  diagrams  represent,  approxi- 
mately to  scale,  the  points  of  disappearance  in  and  reappear- 
ance from  eclipse  of  the  four  satellites  as  seen  in  an  invert- 
ing telescope  during  the  months  of  December  1883  and 
February  1884.  After  what  I have  said,  they  ought  to  be 
perfectly  intelligible. 

It  only  remains,  in  conclusion,  to  refer  to  certain  curious 


JUPITER. 


73 


phenomena,  for  which  the  observer  should  always  be  on  the 
alert.  In  the  case  of  occultations,  to  begin  with,  the  satel- 
lites have  been  seen  apparently  projected  on  the  planet’s 
disc ; although  it  seems  probable  that  they  were  rather  seen 
through  Jupiter’s  limb.  A star  occulted  by  Jupiter  has  been 
seen,  in  a very  large  telescope,  to  fade  away  in  a manner 
which  affords  strong  confirmation  of  this  idea.  When  a 
satellite  begins  its  transit,  it  may  be  traced  fairly  on  to  tho 
planet  as  a brilliant  spot  ] but  it  generally  disappears  after 
getting  some  distance  within  the  limb,  its  reappearance 
happening  as  it  is  about  to  pass  off  on  the  other  side  of  the 
planet.  I have  said  that  a satellite  ‘generally’  disappears 
when  well  within  the  planet’s  limb  ; but  very  remarkable 
exceptions  indeed  to  this  rule  have  been  witnessed. 

I have  myself  seen  Satellite  III.  quite  as  dark  in  appear- 
ance as  its  own  shadow  when  transiting  Jupiter,  and  the 
same  effect  has  been  noticed  with  IV.,  and  even,  more 
rarely,  with  II.  Again,  the  shadows,  although  normally  like 
ink-spots,  have  been  seen  of  curiously  diversified  colours. 
Those  of  Satellites  I.  and  II.  have  been  noted  as  grey.  I 
saw  the  shadow  of  II.  a chocolate-brown  in  October  1880, 
and  attempted  to  account  for  this  phenomenon  by  the  sup- 
position that  the  sun’s  light  must  have  been  shut  off  from 
a part  of  Jupiter’s  surface  glowing  with  a dull  red  heat. 
But  as  I remarked  in  connection  with  the  phenomena  of 
the  belts,  my  object  here  is  not  to  give  a mere  list  of  prior 
observations,  but  rather  to  direct  the  beginner  in  his  own. 
Under  any  circumstances  I would  fain  hope  that  I have 
said  enough  to  stimulate  him  to  pursue  the  study  of  so 
interesting  a system  as  that  of  which  I am  treating,  and  to 
impress  him  with  something  of  the  charm  and  pleasure  of 
the  investigation  of  the  leading  characteristics  of  the  Jovian 
system,  even  in  so  small  an  instrument  as  that  whose  use  I 
am  presupposing. 


74  HOURS  WITH  A THREE-INCH  TELESCOPE. 


CHAPTER  IX. 

SATURN. 


Coming  as  Saturn  does  into  opposition  to  the  sun  during 
the  early  morning  of  November  29, 1 with  his  rings  nearly  at 
their  greatest  opening,  and  southing  in  this  country  at  an 
altitude  of  between  50°  and  6o°,  the  planet  could  hardly  be 
in  a more  favourable  position  for  the  observer  than  he  is  at 
present.  He  will  be  found  in  the  sky  just  now  to  the 
north  and  west  of  Aldebaran  (‘The  Stars  in  their  Sea- 
sons,’ Map  I.),  and  will 
be  instantly  identified  by 
the  leaden  hue  of  his 
light  as  contrasted  with 
the  red  colour  of  ‘The 
Bull’s  Eye.’  The  sub- 
joined sketch  of  the 
planet  was  made  at  the 
telescope  with  a power 
of  204  on  the  night  of 

Fig.  33.— Saturn,  18S3,  Nov.  13,  nh.  45m.  XT  . . 

g.m.t.  Power,  204.  November  13,  at  iTh. 


45m.  p.m. 

The  flattened  figure  of  the  planet  will  at  once  strike  the 
observer’s  eye.  In  other  words,  he  will  note  that  instead 
of  presenting  a circular  disc,  the  outline  of  Saturn  is  very 
perceptibly  elliptical — or,  as  it  is  commonly  called,  ‘oval' — 
the  longest  diameter  of  the  ellipse  being  in  the  direction  of 
his  equator.  Technically,  his  figure  would  be  described  as 


This  was  written  in  1SS3. 


SA  TURA. 


75 


an  oblate  spheroid,  which,  put  into  plain  English,  means 
that  instead  of  the  planet  being  a perfect  sphere,  he  is,  as  it 
were,  turnip-shaped,  i. e. , flattened  at  the  poles  and  bulged 
out  at  the  equator.  This  effect  of  the  rapid  rotation  of 
Saturn  needs  no  further  mention  here.  The  southern  part 
of  the  globe  (that  which  is  uppermost  in  the  telescope)  will 
be  seen  to  be  covered  by  a perceptible  dark  shading,  which, 
however,  terminates  with  a well-defined  edge  not  far  from 
the  planet’s  equator.  Below  (north)  of  this  is  a bright  equa- 
torial band.  The  general  yellow  tint  of  the  ball  is  also  a 
notable  feature.  Where  the  ring  crosses  Saturn’s  disc  a 
broad  line  of  shading  will  be  observed,  and  a careful  and 
attentive  study  of  this  under  good  definition  will  show  that 
it  consists  of  two,parts,  a dark,  broad  line  of  shading  cross- 
ing, as  I have  said,  the  face  of  the  planet  ; and  seemingly 
superposed  upon  it,  and  in  contact  with  the  inner  edge  of 
the  ring,  a very  narrow  black  line.  This  latter  is  the  real 
shadow  of  the  ring  upon  the  planet.  The  broader  stripe  is 
a part  of  the  strange  interior  dusky  or  ‘ crape  ’ ring,  of  which 
I shall  speak  immediately.  If  we  turn  now  to  the  ring 
itself,  we  shall  perceive  that  it  really  consists  of  two  concen- 
tric ones,  the  inner  one  being  very  much  broader,  and  not- 
ably brighter  than  the  outer  one,  or  than  the  dusky  capping 
on  the  southern  hemisphere  of  the  planet.  A narrow  dark 
line  will  be  seen  to  separate  the  inner  ring  from  the  outer 
one.  In  telescopes  of  four  inches  of  aperture  and  upwards 
this  dark  division  is  traceable  right  round  the  ring.  With  a 
three-inch  telescope  it  will,  under  favourable  circumstances, 
be  well  seen  in  the  ‘ anste  ’ (the  eastern  and  western  portions 
of  the  ring),  but  will  scarcely  be  fairly  discernible  entirely 
round.  At  moments  of  the  best  definition  the  shadow  of 
Saturn  will  be  seen,  as  drawn  above,  projected  on  the  inner 
ring  only,  the  black  line,  known  from  its  discoverer  as 
‘ Cassini’s  Division,’  at  once  bounding  it  and  the  planet’s 
south  pole  on  the  south.  The  ‘ crape  ’ ring  to  which  refer- 
ence has  previously  been  made  is  just  beyond  the  power  of 
our  instrument.  On  nights  when  atmospheric  conditions 


•K  Siji 


SA  TURN. 


77 


admit,  however,  of  the  use  of  a high  power,  faint  indications 
of  it  may  be  seen  in  the  form  of  a seeming  ill-defined  shad- 
ing away  of  the  inner  edge  of  the  broad  interior  ring,  in  the 
ansae.  No  connection,  though,  is  traceable  between  this 
and  that  portion  of  the  dark  ring  which  is  seen  crossing 
Saturn’s  disc  ; albeit  in  larger  instruments  the  whole 
elliptical  outline  is  seen  to  be  continuous — save,  of  course, 
where  the  planet  itself  is  superposed  on  it.  The  rings  are 
known  to  astronomers  as  A,  B,  and  C ; A being  the  outer 
ring,  separated  from  B,  the  broad  bright  inner  one,  by 
Cassini’s  division,  and  C the  innermost  crape  ring  which 
I have  just  been  describing.  Ring  A itself  has  been  seen 
to  be  further  cut  into  two  by  a division  known  as  Encke’s  ; 
but  assuredly  this  has  never  been  effected  with  a three-inch 
telescope. 

Saturn,  as  may  be  learned  from  ever}'  primer  of  astro- 
nomy, is  attended  by  eight  satellites,  of  which  three  are 
wholly  invisible  save  in  large  and  powerful  telescopes.  I 
find  that  by  hiding  Saturn  behind  a very  thick  wire  in  the 
eye  piece,  or  by  any  cognate  contrivance,  the  two  known  as 
Tethys  and  Dione  may  sometimes  be  glimpsed  on  a dark 
night.  That  named  Rhea  was  even  visible  in  the  bright 
moonlight  while  the  sketch  of  the  planet  given  on  a 
previous  page  was  being  made,  and  I fancied  (although  it 
may  have  been  only  fancy)  that  Tethys  sometimes  flickered 
up  for  a few'  consecutive  seconds  at  distant  intervals.  Inas- 
much then  as,  under  sufficiently  favourable  circumstances, 
the  possessor  of  a first  class  three-inch  telescope  may  hope  to 
perceive  four,  or  barely  possibly  even  five,  out  of  the  eight 
satellites  by  which  Saturn  is  attended,  I here  give  a drawing 
to  scale  of  their  orbits,  by  the  aid  of  which  the  student  may 
recognise  them. 

The  arrows  show'  the  direction  of  their  motion  ; in  con- 
nection with  which  it  may  be  noted  that,  at  first  sight,  this 
motion  may  seem  to  be  7-etrogrcide.  It  must,  how'ever,  be 
borne  in  mind  that  we  are  looking  at  Saturn’s  south  pole, 
and,  so  to  speak,  viewing  the  orbits  of  his  moons  from 


78  HOURS  WITH  A THREE-INCH  TELESCOPE. 


underneath.  In  1899,  when  the  north  pole  of  the  planet 
will  be  presented  to  us  practically  as  the  south  pole  is  at 
present,  the  satellites  will  be  seen  to  be  travelling  in  the 
same  direction  as  those  of  Jupiter,  or  as  our  own  moon  &c. 
Tethys  and  Dione  must  always  be  difficult  objects  in  a sma'l 
instrument,  and  require,  as  I have  said,  the  planet  to  be 
hidden,  and  a moonless  sky,  to  be  even  glimpsed  in  a 
three-inch  telescope.  Rhea  is  a little  easier,  but  will  be  best 
seen  when  at  its  greatest  east  or  west  elongation.  Titan, 
shining  as  a small  eighth  magnitude  star,  is  practically 
always  visible.  It  occasionally  transits  the  disc  of  Saturn, 
and  under  these  circumstances  its  shadow  has  even  been 
seen  as  a tiny  black  dot,  crossing  the  face  of  the  planet, 
with  only  2§  in.  of  aperture.  The  light  of  Iapetus  is  (from 
some  cause  at  present  imperfectly  understood)  variable. 
This  satellite  is  very  markedly  brighter  when  at  its  western 
elongation. 

Such  are  the  most  salient  features  of  this  wonderful 
planet,  as  seen  in  a small  telescope.  I can  only  express 
a hope  that  my  description  of  them  may  set  the  student 
seriously  to  work  examining  them  for  himself,  with  the  best 
instrumental  means  he  can  obtain.  The  interest  which  the 
contemplation  of  so  wonderful  and  beautiful  an  object  must 
perforce  excite  will,  almost  of  necessity,  induce  a desire  for 
tuller  information  concerning  it.  For  such  information,  of 
a practically  exhaustive  character,  no  better  or  more  inte- 
resting a work  could  possibly  be  found  than  ‘Saturn  ard 
its  System,’  by  the  editor  of  ‘Knowledge,’  which  has  been 
described,  with  perhaps  as  little  flattery  as  ever  appeared  in 
a critique,  as  ‘ one  of  the  most  masterly  monographs  on  an 
astronomical  subject  in  the  English  language.’ 


79 


CHAPTER  X. 

URANUS  AND  NEPTUNE. 

In  one  sense  these  chapters  would  be  incomplete  were  no 
reference  made  in  them  to  the  aspect  in  our  instrument  of 
the  (as  far  as  is  at  present  known)  two  outermost  members 
of  our  solar  system.  A three-inch  telescope  is  hardly  the 
one  which  the  observer  would  select  for  the  scrutiny  of 
these  dim  and  distant  orbs ; but,  if  we  are  to  view  them  at 
all,  we  must  employ  the  optical  means  at  our  disposal,  and 
make  the  most  of  what  we  possess.  Uranus  is  nowrl  coming 
into  a favourable  position  for  examination.  He  is  so  close 
to  /3  Virginis  as  to  be  well  within  a tolerably  low’  power  field 
together  with  that  star.  Even  with  a power  that  will  include 
the  star  and  the  planet  in  the  same  field  a very  notable 
difference  in  their  aspect  is  perceptible ; 
but  we  must  use  all  the  magnification  that 
our  telescope  will  admit  of  to  see  Uranus 
to  the  greatest  advantage ; and  under  such 
a power  he  was  absolutely  isolated  in  the 
field  of  view  wrhen  the  subjoined  drawing 
was  made. 

It  will  be  seen  that  the  planet  exhibits  Fig.  35.  — Uranus, 

i r -lit  March  16,  1884, 

the  appearance  of  a small  greyish-blue  9h.  i5m.  g.m.t. 
disc,  seemingly  perfectly  uniform  in  tint,  Power’  zs°- 
and  without  markings  of  any  kind.  That  the  disc,  how- 
ever, is  planetary  and  not  stellar  is  evident  enough  with 
the  power  we  are  using,  and  may  be  rendered  even  more 

1 This  was  written  in  March  1884. 


8o  HOURS  WITH  A THREE-INCH  TELESCOPE. 


apparent  by  turning  the  telescope  on  to  ft  Virginis,  and 
comparing  the  two  images.  The  difference  between  the 
pale  diffused  disc  of  Uranus  and  the  sharp  and  brilliant  one 
of  the  star,  with  its  single  diffraction  ring  (wholly  wanting, 
of  course,  in  the  former),  will  instantly  strike  the  eve.  That, 
however,  much  more  will  ever  be  found  out  as  to  the 
physical  aspect  of  the  planet  is — in  the  existing  state  of 
practical  optics— doubtful.  Light  itself,  travelling  at  the 
rate  of  nearly  -187,000  miles  in  a second,  takes  more  than 
2 hours  and  28  minutes  to  pass  across  the  stupendous 
interval  which  separates  us  from  this  remote  world  when  he 
is  in  opposition  to  the  sun.  The  student  will  have  read 
that  Uranus  is  attended  by  four  satellites;  but  it  is  quite 
needless  to  add  that  they  are  utterly  beyond  the  power  of 
the  telescope  we  are  employing.  Probably  no  human  eye, 
save  one,  has  ever  seen  these  extremely  minute  objects  with 
less  than  about  7 inches  of  aperture,  the  solitary7  observer  to 
whom  I refer  being  that  excellent  and  almost  supernatural!}7 
keen-sighted  one,  Mr.  I.  W.  Ward,  of  Belfast,  who  did 
actually  glimpse  the  two  outer  satellites  with  only  4-3  in.  of 
aperture  on  many  occasions  during  the  early  part  of  the 
year  1876!  The  reality  of  this  quasi-miraculous  feat  was 
placed  beyond  doubt  by  the  subsequent  comparison  of  Mr. 
Ward’s  diagrams  made  at  the  telescope  with  Mr.  Marth’s 
calculated  ephemerides  of  the  satellites.  Uranus,  1 may- 
add,  is  just  visible  to  the  naked  eye.  Of  Neptune  little 
need  be  said.  He  will  be  well  placed  next  November  for 
the  observer  in  Taurus,  about  6°  south  of  the  Pleiades.  In 
a three-inch  telescope,  with  a power  of  250,  he  looks  some- 
thing like  an  eighth  magnitude  star ; but,  as  in  the  case  of 
Uranus,  he  exhibits  no  diffraction  rings  and  is  dimmer  than 
an  ordinary  fixed  star.  It,  however,  requires  a large  and 
powerful  telescope  to  exhibit  Neptune  with  an  unmis- 
takably planetary  disc,  and  the  observer  with  an  instrument 
of  the  size  of  that  whose  use  is  presupposed  in  these  pages 
may  be  contented  if  he  can  fairly  satisfy  himself  that  it  is 
not  a star  that  he  is  looking  at. 


CHAPTER  XI. 


DRAWING  THE  PLANETS. 

Probably  in  no  way  could  our  knowledge  of  the  physical 
structure  of  the  planets  be  more  effectually  advanced  than 
by  the  comparison  of  numerous  carefully  executed  and 
accurate  sketches  of  their  superficial  detail,  made  at  sufficient 
intervals  ; and  very  notably  does  this  apply  to  the  three 
bodies  immediately  exterior  to  the  earth — Mars,  Jupiter, 
and  Saturn.  It  is  more  especially,  then,  to  facilitate  the 
delineation  of  these  particular  planets 
that  the  present  chapter  is  written.  I 
do  not,  however,  mean  here  to  enter  into 
the  question  from  an  artistic  point  of 
view  ; all  I propose  to  do  is  to  instruct 
the  student  how  to  draw  the  outlines 
of  the  planets  with  ease  and  accuracy  ; 
as  this  always  forms  a stumbling  block 
in  the  way  of  the  beginner.  Com- 
mencing with  Mars,  he  is,  at  present,1 
sensibly  circular,  and  subtends  an 
angle  of  some  17".  Hence  we  need  only  take  a- pair  of 
compasses,  and  with  centre  C'  (fig.  36)  and  a radius  C'A 
or  C'D  of  half  an  inch,  describe  a circle  AC  D B— of  course 
1 in.  in  diameter— to  obtain  the  outline  we  require.  But 
Mars  is  sufficiently  near  to  the  earth  to  exhibit  a sensible 
phase,  and  when  near  ‘quadrature’  with  the  sun  is  very 
perceptibly  gibbous— or  like  the  moon  about  a couple  of  days 
1 This  was  written  in  February  18S4. 

G 


82  HOURS  WITH  A THREE-INCH  TELESCOPE. 


before  or  after  she  is  full.  Suppose,  then,  that  we  wanted 
to  draw  the  outline  of  Mars  on  May  15,  1884.  Turning  to 
p.  468  of  the  ‘ Nautical  Almanac,’  we  find  that  only  0-9  of 
that  diameter  of  the  planet  passing  through  the  sun  is  illumi- 
nated (this  is  not  a strictly  scientific  description,  but  will  be 
better  understood  than  ‘ the  versed  sine  of  the  illuminated 
portion  of  the  disc  ’).  Let  C D be  this  diameter,  and  A B one 
at  right  angles  to  it.  Then  C E will  be  the  part  in  light.  First, 


with  cefftre  C as  before,  and  radius  C'l),  describe  the  circle 
ACBD.  Measure  off  one-tenth  of  CD  to  E.  Join  A E, 
B E,  and  bisect  A E in  G and  B E in  H ; from  G draw  G F 
at  right  angles  to  A E,  and  from  H,  H F at  right  angles  to 
B E.  Finally,  from  F,  where  these  last  two  lines  intersect, 
and  with  radius  FE  or  FA,  describe  the  arc  AEB. 
Then  will  AEBC  represent  the  outline  of  Mars  at  our 
specified  period 


DRAWING  THE  PLANETS. 


83 


If  now  we  try  to  draw  Jupiter  as  we  see  it  in  the  telescope, 
we  perceive  at  once,  from  its  pronounced  elliptical  outline,  that 
it  is  impossible  to  do  so,  merely  by  the  aid  of  compasses,  at 
all.  The  equatorial  diameter  of  Jupiter  just  now  1 approaches 
43",  so  that,  adhering  to  our  original  scale,  we  may  represent 
this  in  fig.  37  by  eg,  which  we  must  make  equal  to  2 ‘4  in. 
The  preface  to  the  ‘Nautical  Almanac’  tells  us  that  Jupiter’s 
polar  diameter  is  only  -939  of  his  equatorial  one,  so  that  we 
take  pa  — 2'25  in.  Then  from  the  centre  c,  where  the  two 
diameters  cut  each  other  (of  course,  at  right  angles),  we 
take  the  distance  c e or  c q in  the  compasses,  and  placing 
one  leg  of  the  compasses  on  p or  a , move  them  about  until 
the  other  leg  touches  the  line  c q in  the  points  / and  f. 
Into  these  points,  technically  called  the  foci  of  the  ellipse, 
we  stick  two  pins,  and  round  them  tie  a loop  of  thread  of 
such  length  that  when  stretched  tight  by  a pencil,  the  pencil 
point  shall  just  touch  either  a , e,  p,  or  q.  f p f represents 
this  thread  in  our  figure,  and  if  it  be  kept  tightly  stretched 
as  the  pencil  is  carried  round,  the  curve  p e a q will  be  the 
correct  elliptical  outline  of  Jupiter  to  our  adopted  scale. 

The  description  of  the  outline  of  Saturn  and  his  rings 
only  involves  a repetition  of  this  process.  Its  successive 
steps  will  be  understood  by  the  study  of  fig.  38. 

As  the  diameter  of  Saturn  was  17 -8"  on  January  14  of 
the  present  year,1  we  revert  to  our  original  scale  of  1 inch  for 
the  equatorial  diameter  of  the  planet.  But  he  is  even  more 
elliptical  than  Jupiter,  his  polar  axis  only  measuring  ’895 
of  that  passing  through  his  equator  ; so,  to  begin  with,  we 
have  e q — 1 inch,  and  pa  — ’895  inch.  As  before,  with 
one  leg  of  the  compasses  on  p or  a,  and  with  the  distance 
c e or  c q,  we  find  the  foci  //',  and  describe  the  outline 
of  the  ball  of  the  planet.  From  p.  468  of  the  ‘ Nautical 
Almanac  ’ we  ascertain  that,  at  the  epoch  chosen,  the  outer 
major  axis  of  the  outer  ring  0 d was  44-62",  and  its  outer 
minor  axis  id!  19-11";  converting  these  into  linear 
measure  by  a rule-of-three  sum,  we  find  0 d=  2-5  inches, 
1 This  was  written  in  February  1884. 


84  HOURS  WITH  A THREE-INCH  TELESCOPE. 

and  i d' = 1-07  inch.  In  like  manner  we  find  that  the 
inner  major  axis  of  the  inner  ring  d d"  was  29-67",  and 
its  inner  minor  axis  i' d'"  12-71";  quantities  which,  as 
before,  we  turn  into  i-66  inch  and  0-72  inch  respectively. 
Then,  in  the  manner  explained  two  or  three  times  pre- 
viously, we  find  the  foci  Z2,/3,  and  /4,  /*,  insert  our  pins, 
and  describe  the  ellipses  to  which  they  respectively  pertain  ; 
the  result  being  shown  in  our  figure.1 

Possibly  by  this  time  the  beginner  who  has  followed  me 
so  far  may  feel  tempted  to  exclaim,  ‘ Good  gracious  ! am 
I to  go  through  all  these  elaborate  reductions  of  angular 


B 

Fig.  38. 


into  linear  measurements,  these  findings  of  foci,  sticking 
in  of  pins,  carefully  tying  loops  of  thread  of  a rigidly 
accurate  length,  and  all  the  rest  of  it,  every  time  I want  to 
make  a drawing  of  Jupiter  or  Saturn?  ’ To  which  I would 
reply,  ‘Certainly  not.’  The  outline  of  Jupiter  is,  for  our 
present  purpose,  absolutely  invariable,  while  those  of  Mars, 
and  especially  those  of  the  Saturnian  system,  vary  so  slowly 
that  the  outline  once  drawn  will  be  sufficiently  accurate  for 

1 The  relative  dimensions  of  the  Saturnian  system  given  in  the 
‘Nautical  Almanac’  are  notably  erroneous;  but  they  are,  at  present, 
the  best  available. 


DRAWING  THE  PLANETS. 


§5 


many  weeks.  All,  then,  that  the  student  has  to  do  is  to 
transfer  such  outline  to  a sheet  of  what  is  called  in  the 
shops  latten-brass,  and,  cutting  it  very  carefully  out,  to  thus 
make  a stencil-plate.  This  is  held  firmly  down  on  to  the 
paper,  and  very  thick  Indian  ink  rubbed  over  and  round  it 
with  a stencil-brush  or  tooth-brush  with  the  hairs  cut  short, 
the  result  being  a white  figure  of  the  planet  on  a black 
background.  If  latten-brass  cannot  be  procured  card  may 
be  used,  but  the  brass  will  be  found  the  more  satisfactory  of 
the  two.  Furthermore,  for  the  mere  purpose  of  obtaining 
an  outline,  a sharp-pointed  pencil  may  be  run  round  the 
edges  of  the  stencil-plate,  although  the  Indian  ink  will  be 
found  much  more  effective.  In  this  way  I have  myself  for 
some  years  past  prepared  outlines  of  the  planets  for  the 
purpose  of  sketching,  with  results  so  successful  that  I unhesi- 
tatingly recommend  it  to  all  who  may  care  to  address  them- 
selves seriously  to  the  very  interesting  task  of  delineating 
the  detail  visible  on  the  surfaces  of  our  nearest  neighbours 


86  HOURS  WITH  A THREE-INCH  TELESCORE. 


CHAPTER  XII. 

THE  FIXED  STARS  AND  NEBUL/E. 

Night  One. 

In  treating  of  the  fixed  stars  in  this  concluding  chapter,  I 
propose  simply  to  select  a moderate  number  of  typical  and 
interesting  objects  for  description  and  illustration,  and  to 
take  them  from  all  parts  of  the  sky  visible  in  Great  Britain. 
I am  not  writing  for  the  possessor  of  an  equatorially  mounted 
telescope,  furnished  with  graduated  circles.  To  any  one 
possessing  these  means  of  identifying  objects,  the  stellar 
heavens  present  an  inexhaustible  storehouse  of  objects  of 
interest : but  I am  here  addressing  the  owner  of  a three-inch 
telescope,  mounted  on  a simple  pillar-and-claw  stand.  I 
shall,  then,  merely  direct  the  attention  of  the  student  to 
certain  stars,  <Scc.,  marked  in  the  maps  of  ‘ The  Stars  in 
their  Seasons,’ in  the  ‘Knowledge’  Library  Series,  with  a 
probably  rare  reference  to  Proctor’s 
‘Star  Atlas.’  Now  let  us  open  Map  I. 
of  ‘The  Stars  in  their  Seasons,’  and  to- 
wards the  lower  right-hand  corner  we 
shall  find  a star  in  Cetus,  marked  y. 
If  we  are  employing  the  little  device 
illustrated  in  fig.  i (p.  3),  we  must  take 
care  that  the  bar  B M is  as  duly  north 
and  south  as  we  can  place  it,  and  this 
adjustment  being  made,  we  put  on 
our  lowest  power  eye-piece,  and  find  y Ceti  in  the  sky. 
Having  got  it  into  the  middle  of  the  field,  we  exchange 


Fig.  39. — y Ceti. 


THE  FIXED  STARS  AND  NEBULAE. 


87 


the  low  power  for  one  of  160,  and  examine  our  object. 
At  the  first  glance,  probably,  the  student  will  see  nothing 
but  a yellowish  star  of  considerable  brightness  : but,  by 
careful  attention,  he  will  not  be  long  ere  he  catches  its 
small  companion,  seemingly  to  the  left  of,  and  just  below 
a horizontal  line  passing  through  the  larger  star.  Its  blue 
or  dusky  tint  will  at  once  strike  the  observer,  as  well  as  its 
small  size  compared  with  that  of  its  primary.  This  elegant 
pair  form  what  is  known  to  astronomers  as  ‘ a binary 
system  ; ’ in  other  words,  the  stars  are  physically  connected, 
and  the  smaller  star  revolves  round  the  larger  one — or  both 
round  their  common  centre  of  gravity — in  a very  long  period, 
the  exact  duration  of  which  is,  as  yet,  undetermined.  There 
are  other  objects  of  interest  in  Cetus,  but  the  difficulty  of 
identifying  them  compels  me  to  omit  reference  to  them. 
Among  them,  66  Ceti  may  be  mentioned  as  a charming 
pair.  It  may  be  found — with  numerous  other  doubles — on 
Map  III.  of  Proctor’s  ‘Star  Atlas.’ 

Above,  and  to  the  right  of  that  part  of  Cetus  in  which  y 
is  situated,  will  be  seen  a curved  line  of  three  stars,  the  chief 
ones  in  Aries  ; the  bottom,  and  least,  of  which  is  remarkable 
as  being  the  one  of  which  Hooke  wrote  in  1664,  ‘ I took 
notice  that  it  consisted  of  two  small  stars  very  near  together  ; 
a like  instance  to  which  I have  not 
else  met  with  in  all  the  heavens.’  It  is 
almost  needless  to  tell  even  the  be- 
ginner that  double  stars  are  now  num- 
bered by  thousands.  Viewed  with  a 
power  of  160,  y Arietis  presents  the 
appearance  shown  in  fig.  40.  The 
components  of  this  asterism  will  be 
observed  to  be  pretty  nearly  equal 
in  size.  The  (apparently)  lower  and 
smaller  star  of  the  two  will  be  seen  to  be  of  a greyish  hue. 
If  now  the  observer  will  follow  an  imaginary  line  from  y 
through  /?  on  the  map,  it  will  strike  upon  a star,  not 
lettered  there,  but  fairly  well  seen  with  the  naked  eye  to  the 


88  HOURS  WITH  A THREE-INCH  TELESCOPE. 

right  of  a.  This  is  A,  a wide  but  pretty  double.  Here  again 
the  smaller  star  is  more  distinctly  coloured  than  the  larger 
one.  Forming  the  apex  of  a right-angled  triangle  with  a 
and  A Arietis  (whereof  a is  at  the  right  angle)  is  a wide  triple 
star,  14  Arietis.  Sweeping  where  Aries  and  Triangula  are 
conterminous,  several  pairs  of  small  stars  will  pass  across 
the  field  of  view.  Some  2°  (four  times  the  diameter  of  the 
sun  or  moon)  above  and  to  the  right  of  (3  Arietis  (as  seen 
by  the  naked  eye)  will  be  found  a beautiful  close  double 
star,  which  will  most  severely  tax  the  power  of  the  incipient 
observer  to  see  it  fairly  separated.  It  is  179  of  Hour  I.  in 
Piazzi’s  great  catalogue.  The  yellowish  tinge  of  the  larger 
component,  contrasting  with  the  blue  of  the  smaller  one, 
renders  this  a very  pretty  object.  And  now  the  observer 
may  raise  his  telescope  higher  still,  to  that  lovely  object  y 
Andromedse  (above  Triangula  in  the  map).  The  contrast 
between  the  yellow  of  the  large  star  and  the  exquisite  green 
of  its  small  companion  is  very  striking.  7 r Andromedae,  to 
the  right  of  /?,  is  a very  pretty  pair,  the  contrasting  colours 
being,  in  this  case,  very  pale  yellow  and  blue  ; 59,  2 3,  P. 
XXIII.  240,  and  other  beautiful  pairs,  will  be  found  marked 
in  Proctor’s  ‘Atlas.’ 

Exchanging  now  his  high  power  for  the  lowest  one 
supplied  with  his  telescope,  the  beginner  should  fish  a little 
above  and  to  the  right  of  v Andromedae  for  that  most 
remarkable  object,  31  of  Messier’s  catalogue  ; the  well- 
known  great  nebula  in  Andromeda.  Sir  John  Herschel 
quotes  Simon  Marius  as  describing  the  appearance  of  this 
nebula  as  resembling  that  of  a candle  shining  through 
horn,  and  this  really  does  not  give  a bad  idea  of  it  as  viewed 
in  such  an  instrument  as  that  which  we  are  using.  Readers 
of  current  scientific  literature  will  remember  how  a new 
star  shone  up  in  the  very  midst,  and  close  to  the  nucleus 
of  this  nebula,  in  August  1885,  and  which  faded  to  invisi- 
bility early  during  the  present  year  (1886). 

None  of  the  larger  stars  in  Taurus  present  any  features 
of  interest  in  small  telescopes,  x Tauri  is  a somewhat  wide, 


THE  FIXED  STARS  AND  NEBULAE. 


89 


but  pretty  pair.  In  the  Map  I.  of  ‘ The  Stars  in  their 
Seasons,’  which  we  are  supposed  to  be  using,  a trapezium  of 
small  stars  will  be  noted  above  the  words  Aldebara?i  and 
taurus.  x at  the  left-hand  top  coiner  of  this  trapezium. 
Identification  of  the  smaller  ones  without  graduated  circles 
is  almost  hopeless  ; using  a low-power  eye-piece,  though,  the 
Pleiades  present  a fine  spectacle,  and  about  two  diameters 
of  the  moon  above  and  to  the  right  of  £Tauri  will  be  found  a 
pale  elongated  nebula.  A low  eye-piece  too  must  be  used  for 
this.  Nearly  overhead  (in  December  and  January),  Perseus 
will  be  observed — a constellation  rich  in  objects  of  interest,  of 
which,  however,  I can  only  give  an  account  of  a very  few  suit- 
able for  the  instrument  whose  employment  is  presupposed, 
e is  a very  fine  pair,  but  the  smaller 
star  requires  some  little  looking  for. 

It  is  below  and  just  to  the  right  of  its 
primary.  It  is  delineated  in  fig.  41. 

£ Persei  is  really  a quadruple  star, 
but  the  student  will  scarcely  discern 
more  than  three  out  of  its  four  com- 
ponents with  the  aperture  I am  con- 
sidering. 7]  is  another  pretty  pair,  too, 
but  somewhat  difficult  from  the  faint- 
ness of  its  companion.  Perseus  contains  several  interesting 
clusters — notably  one  of  the  most  glorious  fields  of  stars  in 
the  whole  heavens,  in  what  is  called  the  ‘Sword-handle.’  This 
may  be  seen  by  a sharp-sighted  person  with  the  naked  eye, 
between  Perseus  and  Cassiopeia,  as  a bright  spot  in  the  Milky 
Way.  This  superb  object  requires  the  lowest  eye-piece  in 
the  observer’s  possession,  to  do  it  the  smallest  justice.  No 
view  of  it,  however,  with  so  small  an  aperture,  will  give  any 
idea  of  the  gorgeous  effect  it  presents  in  a large  instrument. 

South  of  Aries  and  the  Pleiades  lies  the  straggling  con- 
stellation Eridanus.  It  contains  numerous  interesting  pairs 
of  stars,  which,  in  the  absence  of  Proctor’s  1 Atlas,’  must  be 
swept  for.  It  would  only  tend  to  confusion  to  attempt  to 
localise  them  on  a map  in  which  they  are  not  lettered  nor 


90  HOURS  WITH  A THREE-INCH  TELESCOPE. 


numbered.  32,  39,  55,  and  P.  III.  98,  will  all  be  found  to  be 
beautiful  and  attractive  objects,  and  are  marked  in  Proctor. 
A curious  planetary  nebula,  y IV.  26,  seen  best  with  a 
tolerably  low  power,  will  be  found  there  too. 

Night  Two. 

By  this  time  the  student  will  have  become  tolerably 
familiar  with  his  instrument.  I propose  to  employ  it  to- 
night in  the  examination  of  some  of  the  more  striking 
objects  in  the  glorious  constellation  of  Orion.  And  first  we 
will  turn  it  upon  (3  Orionis  or  Rigel,  fig.  42,  which  will 
furnish  the  young  astronomer  with  good,  if  easy,  preliminary 
practice  in  the  detection  of  small  stars  in  the  neighbourhood 
of  larger  and  more  brilliant  ones.  Probably,  at  first,  his  eye 
will  be  dazzled  with  the  brilliant  blue  coruscations  surround- 
ing Rigel  itself ; but  a little  careful  attention  will  show  just 
above  and  to  the  left  of  it  a small  bluish  point,  as  shown  in 
the  figure.  From  Orion’s  foot  he  may  proceed  to  his 
face,  in  which  we  shall  find  A,  a very  pretty  pair,  tolerably 
close  together,  the  larger  star  being  yellowish,  the  smaller 


Fig.  42. — Rigel.  Fig.  43. — A Orionis. 


one  more  of  a lilac  hue.  Fig.  43  represents  it  as  seen 
with  a power  of  120.  The  lowest,  or  most  easterly  of  the 
three  stars  in  the  Giant’s  belt,  £,  will  next  claim  our  attention, 
and  to  show  this  properly  will  be  a pretty  severe  test  of  the 
excellence  of  the  observer’s  instrument.  As  shown  in  the 
drawing  below,  this  star  is  triple  ; the  principal  and  second 


THE  FIXED  STARS  AND  NEBULAE. 


9i 


stars,  with  a power  of  150,  being  almost  in  contact,  and  the 
third  below  and  to  the  right  of  them.  Some  considerable 
gazing  will  be  required  on  the  part  of  the  beginner  before 
he  succeeds  in  making  out  the  duplicity  of  the  principal 
pair  in  this  asterism.  The  engraving  may  help  him  to 
understand  exactly  what  to  look  for. 


Fig.  44.— £ Orionis. 


Fig.  45. — c t Orionis. 


We  now  turn  to  a,  which  will  be  seen  beneath  £ in  the 
map.  This  is  a triple,  or,  perhaps  more  correctly,  a septuple 
star,  all  the  components  shown  in  fig.  45  being  well  within 
the  same  field  with  a power  of  120. 

The  object  marked  6 in  the  map  is  one  of  the  most  won- 
derful in  the  whole  heavens, 
consisting,  as  it  does,  of  a 
mass  of  nebulous  matter  (now 
known  to  be  glowing  gas  !) 
surrounding,  and  seemingly 
physically  connected  with,  a 
curious  group  of  stars. 

No  woodcut  can  possibly 
do  justice  to  this  most  mar- 
vellous object  : but  in  my 
sketch,  copied  above,  I have 

endeavoured  to  give  some  F!g.  46._fl  (and  42  M.  Nebula)  Orionk 
faint  idea  of  its  aspect  as 

viewed  with  a power  of  80.  The  black  gap  leading  up  to  the 
trapezium  of  four  stars  is  known  as  ‘ the  fish’s  mouth.’ 


92  HOURS  WITH  A THREE-INCH  TELESCOPE. 


The  nebulosity  surrounding  an  isolated  star,  towards  the 
bottom  of  the  field,  will  be  noted.  The  difference  in 
colour  of  the  stars  forming  the  trapezium  will  be  readily 
detected.  There  are  a fifth  and  a sixth  belonging  to  this 
group  ; but  they  are  entirely  beyond  the  power  of  such  an 
instrument  as  that  which  we  are  using. 

Having  gazed  our  fill  on  this  wonderful  sight,  and, 
furthermore,  particularly  scrutinised  the  trapezium  of  stars 
with  the  highest  power  at  our  disposal,  we  will  lower  the 
telescope  a little  to  i Orionis,  a very  pretty  triple,  in  a fine 
field. 

Its  aspect,  as  seen  with  a power  of  120,  is  shown  in 
fig.  47.  The  smallest  of  the  three  stars  will  require 
careful  looking  for  before  the  unpractised  observer  will  see 
it  at  all. 


Fig.  47. — i Orionis.  Fig.  48. — p'  Orionis.  Fig.  49. — 52  Orionis. 


An  even  more  difficult  star  is  p1  Orionis,  represented  in 
fig.  48.  This  will  require  a power  of  150  at  least,  and,  in 
fact,  as  high  a one  as  the  observer  possesses,  to  see  the 
companion  fairly.  The  small  star  is  so  faint  and  difficult 
with  a three-inch  aperture  as  to  form  a very  fair  light-test 
indeed,  p1  may  be  found  by  carrying  an  imaginary  line 
through  the  three  stars  £,  e,  and  8,  in  the  belt,  on  which 
line,  at  double  the  length  of  the  belt  from  8,  it  will  be 
found. 

The  last  illustration  1 shall  give  is  ot  52  Orionis,  a severe 
test  of  the  separating  power  of  such  an  instrument  as  I am 
considering.  At  moments  of  the  finest  vision,  with  the 


THE  FIXED  STARS  AND  NEBULAS. 


93 


highest  power  at  the  observer’s  disposal,  it  will  be  seen  as 
in  fig.  49. 

Such  are  a few  typical  stars  among  a very6 7  mine  of  such 
objects  in  which  the  student  may  well  search  by  sweeping 
for  himself.  Should  he  succeed  in  exhausting  such  a 
treasury  in  one  night’s  work,  he  may  turn  his  telescope 
down  to  Lepus,  where,  inter  alia , he  will  find  a pretty,  and 
somewhat  difficult  pair  in  k.  This  is  the  star  to  the  right  of 
A,  and  just  beneath  t,  in  Map  I.  of  ‘ The  Stars  in  their 
Seasons.’ 

Night  Three. 

In  speaking  of  Taurus  on  p.  89,  I omitted  one  object  in 
the  absence  of  means  for  its  identification.  It  was  118 
Tauri,  which  is  a beautiful  small  pair  ; it  lies  below  f3  on 
the  map.  In  noticing  the  nebula  to  the  north-west  of  £ 
Tauri,  I omitted,  too,  to  add  that  £ itself  is  situated  in  a rather 
pretty  and  curious  field. 

Above  Taurus  lies  the  constellation  Auriga,  to  the 
examination  of  which  we  proceed  to  devote  ourselves.  I 
will  begin  with  14,  a star  just  above  a line  joining  f3  Tauri 
and  1 Aurigie  in  the  map,  and  about  halfway  between  them 
there.  Really  triple,  we  shall  only  be  able  to  see  it  as  a double 
star,  the  components  being  of  a yellowish  tint,  and  about 
half  as  far  again  apart  as  those  of  y Arietis.  A very  pretty- 
pair  will  be  found  in  co  Aurigae.  This  does  not  appear  by 
name  on  the  map,  but  is  about  halfway  between  rj  and  1 
It  is  represented  in  fig.  50. 


Fig.  50. — 10  Auriga;  Fig.  51. — 8 Aurigae. 


6 Aurigae,  as  a close  and  very  unequal  pair,  will  tax  both 

the  instrument  and  the  eyesight  of  the  observer  to  the 


94  HOURS  IVITH  A THREE-INCH  TELESCOPE. 

uttermost  to  see  it  properly.  When  best  seen  it  will  appear 
as  in  fig.  51. 

5 Aurigse  (to  the  south  of  £)  is  another  star  in  which 
the  diversity  of  size  of  the  components  and  their  proximity 
render  its  observation  decidedly  difficult.  The  student  will 
see  both  these  objects  better  with  a high  power  than  with  a 
lower  one.  26  (N.E.  of  (3  Tauri  in  the  map)  is  a pretty 
star,  from  the  contrasted  colours  of  its  components,  and  is 
very  easy  from  their  distance.  The  companion  is  almost 
horizontally  to  the  left  of  the  larger  star.  2 872  is  an 
equally  easy  pair.  It  will  be  found  just  to  the  left  of  the 
solstitial  colure  in  the  map.  225  P.  v.  Aurigse,  to  the  N.E. 
of  26,  must  be  found  by  fishing,  as  it  is  invisible  to  the 
naked  eye.  When  in  the  field  of  the  telescope,  however, 
it  will  be  found  to  be  a close  and  extremely  pretty  little 
pair. 

We  may  now  take  a glance  at  two  or  three  of  the  most 
striking  clusters  of  stars  in  the  constellation  under  review. 
And  first,  M.  38  (north  of  $ Aurigse)  forms  a beautiful  field, 
the  main  cluster  assuming  a cruciform  aspect.  The  telescope 
may  be  moved  about  in  this  neighbourhood,  which  is  a rich 
one.  M.  36  (nearly  due  E.  of  <£)  is  also  very  fine.  M.  37 
(N.  of  the  double  star  225,  previously  described)  is  a glorious 
field,  even  with  such  an  instrument  as  that  which  we  are 
employing.  In  regarding  a nebula  or  cluster,  no  light  should 
be  suffered  to  enter  the  eye  for  some  little  time  before  it  is 
applied  to  the  telescope  ; and  the  observer  should  gaze 
steadily  at  such  an  object  until  the  eye  becomes  accustomed 
to  it,  after  which  hitherto  imperceptible  detail  will  flash  up. 
Another  rich  field  will  be  found  in  y VII.  33  (N.E.  of  /x  in 
the  map). 

Our  next  object  to-night  shall  be  that  beautiful  and 
familiar  double  star  a Geminorum,  or  Castor  (Map  II.  of 
‘ The  Stars  in  their  Seasons  ’).  This,  with  the  instrument  we 
are  employing,  we  shall  find  to  be  a perfectly  easy  object  ; 
in  fact,  were  the  young  observer  furnished  with  the  means 
of  accurately  directing  his  telescope,  Castor  might  be  seen 


THE  FIXED  STARS  AND  NEBULAE. 


9S 


double  in  bright  twilight — or  even  in  broad  daylight.  Its 
telescopic  aspect,  with  a power  of  120,  is  shown  in  fig.  52. 

8 Geminorum  is  another  star  which  will  repay  examina- 
tion. It  will  be  found  in  Map  II.  The  small  purplish 
companion  will  be  seen  above  the  principal  star,  and  just  to 
the  left  of  the  hour  circle  passing  through  it.  k (below 
Pollux  in  the  same  map)  is  a difficult  and  delicate  pair, 
requiring  a first-class  instrument  and  acute  vision  to  see  the 
comes  at  all.  38  in  this  constellation,  though  difficult,  is  a 
decidedly  easier  object  than  k.  In  both  these  stars  the 
contrasted  colours  of  the  companions  are  very  fine.  Many 
other  objects  will  be  found,  but,  being  invisible  to  the  naked 
eye,  they  are  by  no  means  easy  to  pick  up  without  an 
equatorial  mounting. 


Fig.  52. — Castor.  Fig.  53. — 66  Cancri, 


Cancer  is  not  a constellation  containing  many  objects  of 
interest  within  the  power  of  a three-inch  telescope.  Never- 
theless the  student  will  see  (as  a double  star  (it  is  really 
triple).  <j>‘2  is  another  object,  approximately  as  easy  to  see 
as  £.  66  Cancri  is  decidedly  more  difficult ; for,  although 

the  components  are  about  the  same  distance  apart  as  those 
of  <£'2,  their  considerable  inequality  makes  the  comes  look 
small  by  contrast.  Fig.  53  exhibits  it  as  seen  when  best 
defined  with  a power  of  160. 

1 Cancri  is  chiefly  interesting  from  the  contrasted  colours 
of  its  components.  They  are,  relatively,  very  wide  apart. 
Should  the  observer  possess  a day  eye-piece,  he  may  put  it 
on  to  scrutinise  the  Prsesepe  with.  At  all  events,  he  must 
use  the  lowest  power  he  has.  The  same  eye-piece  may  be 


96  HOURS  WITH  A THREE-INCH  TELESCOPE . 


Fig.  54. — y Leonis. 


retained  to  look  at  another  cluster,  67  Messier,  somewhat 
to  the  west,  or  right,  of  a in  the  sky. 

And  now  we  arrive  at  a star  which,  while  scarcely 
affording  a crucial  test,  yet  requires  a very  good  eye  and 
instrument  to  see  it  well  and  cleanly  separated.  I refer 
to  the  familiar  one,  y Leonis  (Map  III.  ‘ The  Stars  in  their 
Seasons’),  which,  with  a power  of  160,  should  present  the 
appearance  indicated  in  fig.  54. 

A more  difficult  object,  and  one  which  will  severely  tax 
the  powers,  both  optical  and  visual,  of  the  observer,  is 
1 Leonis  (Map  III.).  54  Leonis  is  a 

charming  object.  There  are  a very  great 
many  small  pairs  in  Leo  ; but  the  remarks 
which  I have  made  above  in  connection 
with  telescopic  stars  in  Gemini  are  equally 
applicable  here.  If  the  student  will  fish 
about  the  apex  of  an  equilateral  triangle, 
whereof  a and  y Leonis  form  the  extremi- 
ties of  the  base  (to  the  left,  or  east,  of  the  line  joining  them), 
with  the  lowest  power  at  his  disposal,  he  will  find  himself  in 
a region  rich  in  nebulae. 

Underneath  Leo  in  the  maps  will  be  found  the  foolish 
modern  constellation  of  the  Sextant.  35  Sextantis  (about  5" 
S.E.  of  p Leonis)  is  worth  looking  at,  as  a curious  disagree- 
ment exists  as  to  the  colour  of  the  comes.  There  is  a bright 
nebula,  too,  worth  examination,  in  Sextans.  It  is  163  of 
Sir  William  Herschel’s  first  catalogue. 

Hydra,  straggling  across  the  sky  beneath  Cancer,  Sex- 
tans, Crater,  Corvus,  Virgo,  and  Libra,  contains  a consider- 
able number  of  interesting  objects,  though  but  few  of  them 
are  susceptible  of  easy  recognition,  e Hydra  is  a fine  pair, 
but  difficult  with  such  an  instrument  as  we  are  employing, 
on  account  of  the  proximity  of  its  components,  and  of  their 
disparity  in  size.  Of  the  objects  in  Crater  and  Corvus 
(two  figures  perched  by  the  map-makers  on  Hydra’s  back), 
I need  here  only  allude  to  17  Crateris,  an  easy  double  star, 
with  prettily  contrasted  colours ; and  to  S Corvi,  wider 


THE  FIXED  STARS  AND  NEBULA7.. 


97 


apart  still,  but  exhibiting  even  more  prominent  tints  in 
its  components.  About  three-quarters  of  the  way  upon 
an  imaginary  line  drawn  from  a to  8 Corvi  will  be  found  a 
nebula,  65  of  Sir  William  Herschel’s  first  catalogue.  By 
this  time  the  incipient  astronomer  will  probably  feel  that 
he  has  accomplished  a fairly  good  night’s  work.  Our  next 
night  we  will  devote  to  Virgo  and  the  neighbouring  region 
of  the  sky. 

Night  Four. 

Before  beginning  our  examination  of  the  constellation 
Virgo  to-night,  I will  return  to  that  of  Hydra  for  the  pur- 
pose of  looking  at  a very  wonderful  object,  omitted  in  the 
description  on  the  preceding  page.  The  student  will  find 
it  by  fishing  with  a power  of  100  or  so  about  2°  (four  dia- 
meters of  the  moon)  to  the  south  of  /x  Hydrae  (Map  III.). 
It  is  No.  27  of  Herschel’s  fourth  catalogue,  and  is  one  of 
the  most  remarkable  planetary  nebulae  in  the  heavens.  Un- 
like nebulae  generally,  this  will  bear  considerable  magnifying 
power.  It  will  be  seen  as  a pale  blue  disc,  looking  just 
like  the  ghost  of  Jupiter.  As  Huggins  has  shown  that  it  is 
gaseous,  the  sharpness  of  its  outline  is  very  curious. 


Fig.  55- 1 — y Virginis.  Fig.  56. — e Bootis.  Fig.  57. — f Bootis. 


Turning  now  to  Virgo,  I will  begin  with  that  most 
interesting  star  y,  which  is  shown  in  fig.  55,  as  seen  with  a 
power  of  160.  When  first  observed  by  Herschel,  in  1790, 

1 The  letters  S and  N in  this  and  subsequent  figures  indicate  the 
South  and  North  parts  of  the  field  of  view  ; while  the  arrow  shows  the 
apparent  direction  of  the  star’s  diurnal  motion. 

H 


98  HOURS  WITH  A THREE-INCH  TELESCOPE. 


the  components  of  this  star  were  nearly  6"  apart,  but  were 
approaching  each  ocher;  and  in  1836  were  so  practically 
superposed  as  to  appear  single  under  the  very  highest  power 
that  Admiral  Smyth  could  apply  to  them  upon  his  5^9  inch 
achromatic.  Since  that  time  they  have  been  separating, 
and  their  distance  at  present  amounts  to  about  5",  so  that 
they  form  an  easy  pair  in  the  instrument  we  are  using.  6 
Yirginis  (Map.  V.)  is  a very  pretty  and  interesting  triple  ; the 
third  star,  which  is  nine  times  as  far  from  the  large  one  as 
its  more  obvious  companion,  will  require  a dark  night  and 
pretty  sharp  sight  to  see  it  well.  There  are  very  many 
beautiful  and  interesting  pairs  of  stars  in  Virgo  ; but  as  they 
are  mostly  below  the  sixth  magnitude  they  are  not  marked 
in  the  maps  whose  employment  I am  presupposing,  and 
no  amount  of  descripcion  would  enable  the  reader  to  identify 
them.  Fortunately,  simple  sweeping,  in  the  marvellous 
region  to  which  I am  about  to  introduce  the  reader,  will 
suffice  to  enable  him  to  pick  up  many  of  the  wonderful 
mass  of  nebulae  collected  within  the  area  roughly  bounded 
by  e,  8,  y,  r),  and  /3  Virginis,  and  (3  Leonis.  If  the  student 
will  arm  his  instrument  with  a power  of  about  40,  and  sweep 
slowly  over  that  part  of  the  sky  contained  within  the  curve 
drawn  through  the  stars  I have  named  (Map  V.),  he  cannot 
fail  to  be  astonished  and  pleased  at  the  wealth  of  nebulous 
objects,  and  the  pretty  fields  of  stars  that  he  will  encounter. 
One  of  these  curious  objects  is  shaped  like  a boy's  kite.  A 
few  are  resolvable  into  stars  in  some  of  the  enormous  tele- 
scopes now  comparatively  common.  Others  are  unmistak- 
ably gaseous. 

Above  Virgo  is  situated  Coma  Berenices,  easily  recog- 
nisable in  the  sky  by  the  coarse  cluster  of  stars  in  its  north- 
western portion.  If  the  reader  will  draw  an  imaginary  line 
from  a through  36  on  Mao  V.,  then  at  about  three  times  as 
far  to  the  right  of  36  as  36  is  to  the  right  of  a,  and  a little 
above  such  line,  will  be  found  24  Comte,  a wide  double  star, 
but  interesting  from  the  beautiful  contrast  of  orange  and 
pale  purple  presented  by  its  components.  Just  above,  and 


THE  FIXED  STARS  AND  NEBULAE. 


59 


to  the  left  of  a Comae  (Map  V.),  what  will  appear  like  a 
nebula  will  be  found.  It  is  53  of  Messier’s  catalogue,  and 
is  reahy  an  immense  mass  of  tiny  stars  ; but  it  requires  a 
much  more  powerful  instrument  than  ours  to  show  this. 
Other  nebulae,  mostly  faint,  will  be  found  among  the  cluster 
of  stars  to  which  I have  previously  referred. 

Adjoining  Coma  Berenices  above  lies  Canes  Venatici,  ot 
which  the  chief  star,  a,  12,  or  Cor  Caroli — for  it  has  all 
three  designations — is  a widish  double.  About  one-third 
of  the  way  between  Cor  Caroli  and  8 Leonis  2 Canurn  will 
be  found — a close  pair,  with  prettily  contrasted  colours. 
There  are  numerous  other  pairs  in  this  constellation,  but, 
for  the  so  often  reiterated  reason,  I can  give  no  intelligible 
directions  for  finding  them.  In  the  case  of  more  than  one 
of  the  remarkable  nebulae,  however,  contained  in  it,  I trust 
to  be  more  successful  in  pointing  out  their  whereabouts. 
30  (6  diameters  of  the  moon)  to  the  south-west  of  r)  Ursae 
Majoris,  the  star  at  the  end  of  the  Great  Bear’s  tail,  will  be 
found  two  rather  dim  nebulae,  nearly  touching  each  other. 
This  is  Messier  51,  the  astonishing  Spiral  nebula,  which,  as 
seen  in  Lord  Rosse’s  great  telescope,  has  been  pictured  in 
so  many  works  on  astronomy.  About  midway  between 
Arcturus  and  Cor  Caroli,  but  rather  nearer  the  former  (Map 

V. ),  will  be  found  a bright  nebula,  Messier  3,  which  large 
telescopes  resolve  into  a brilliant  condensed  cluster  of 
minute  stars.  Some  2\°  to  the  north-west  of  Cor  Caroli  is 
a nebula,  94  Messier,  which,  though  small,  is  sufficiently 
conspicuous  in  the  class  of  instrument  we  are  using.  Other 
nebulae  in  this  constellation  may  be  picked  up  by  fishing, 
especially  in  the  region  between  a Canum  Venaticorum  and 
£ Ursae  Majoris. 

The  constellation  Bootes,  at  which  we  now  arrive  (Map 

VI.  of  ‘The  Stars  in  their  Seasons’),  will  be  found  a very 
mine  of  objects  of  interest  by  the  incipient  observer.  We 
will  begin  by  turning  our  instrument,  armed  with  a power  of 
160,  upon  e,  a star  which  Struve  well  described  as  ‘pulcher- 
rima  ’ (or  most  beautiful).  So  viewed  it  will  be  seen  as  in 

h 2 


loo  HOURS  WITH  A THREE-INCH  TELE  SCORE. 


fig.  56,  the  larger  star  being  yellow,  and  the  companion  a 
bluish-green.  7 r Bootis,  an  interesting  and  easy  pair,  when 
viewed  with  a power  of  160  will  be  found  to  present  the 
appearance  shown  in  fig.  58.  $ Bootis  is  a little  closer 

and  somewhat  more  unequal  pair,  the  colours  of  the  com- 
ponents, moreover,  being  more  strongly  contrasted  than  in 
the  case  of  the  previous  star.  It  is  shown  in  fig  57.  1 is 

a wide  and  easy  pair,  which  it  is  needless  to  figure.  44 
Bootis,  shown  in  fig.  59,  as  seen  with  a power  of  160,  is 
interesting  from  the  contrasted  colours  of  its  components. 
It  is  not  numbered  in  the  map,  but  is  one  of  two  small 
stars  forming  a triangle  with  /?  and  6 Bootis  in  it.  Nor  is 


Fig.  58. — 7r  Bootis.  Fig.  59. — 44  Bootis.  Fig.  60. — 39  Bootis. 


our  next  object,  39  Bootis,  numbered  ; but  it  is  the  north- 
western of  the  pair  of  stars  in  the  map,  and  will  be  found 
in  the  sky,  a little  above,  and  to  the  right  of  44.  In  this, 
again,  the  colours  are  prettily  contrasted.  Its  aspect  as 
viewed  with  the  same  power  as  the  preceding  objects  is 
represented  in  fig.  60.  k Bootis,  on  the  confines  of  Canes 
Venatici,  is  a wider,  and  much  more  unequal  pair.  It  is 
shown  in  fig.  61.  On  a line  drawn  from  Spica  Virginis  to 
£ Bootis,  and  about  n°  south  (and  a little  east)  of  Arcturus, 
will  be  found  the  very  pretty  and  interesting  double  star 
which  1 have  drawn  in  fig.  62.  It  is  69  of  the  fourteenth 
hour  of  Piazzi’s  catalogue.  The  difference  in  colour  of  the 
components  of  this  pair  will  at  once  strike  the  observer.  He 


THE  FIXED  STARS  AND  NEBULA!.  ioj 

will,  though,  probably  be  puzzled  to  say  exactly  what  the 
colour  of  the  smaller  star  is,  very  discrepant  conclusions  on 
this  subject  having  been  arrived  at.  Some  8^°  to  the  west, 
and  just  to  the  north  of  Arcturus,  we  shall  find  a very  beau- 
tiful object,  the  star  i Bootis,  shown  in  fig.  63.  At  the 
first  glance  the  student  will  observe  two  stars,  nearly  of 
the  same  magnitude,  and  wide  apart.  It  is  the  upper, 
or  southern  one  of  them,  to  which  our  attention  must  be 
directed.  Looking  at  it  carefully,  we  shall  note  the  minute 
blue  star  shown  in  fig.  63,  to  the  south,  and  very  slightly 
to  the  east  of  its  primary.  I have  omitted  the  second 
large  star  of  which  I have  just  spoken  from  the  diagram, 


Fig.  61. — k Bootis.  Fig.  62. — P.  xiv.  6c.  Fig.  63. — 1 Bootis. 


inasmuch  as,  using  the  scale  to  which  it  is  drawn,  such  star 
would  be  just  out  of  the  northern,  or  lower,  portion  of  the 
field.  Finally,  the  student  may,  if  he  likes,  look  at  £ Bootis 
with  the  very  highest  power  at  his  command  ; but,  under 
the  most  favourable  circumstances,  he  will  only  succeed  in 
so  far  converting  it  into  a slightly  egg-shaped  object  as  to 
show  that  it  is  not  single.  Such  are  a few  of  the  most  easily 
identifiable  objects  in  this  constellation.  The  number  of 
purely  telescopic  double  stars  is  very  large  indeed  ; but 
their  necessary  absence  from  our  map  of  reference,  and  the 
impossibility  of  recognising  them  without  an  equatorial  pro- 
vided with  graduated  circles,  renders  the  mere  mention  of 
them  here  sufficient. 


102  HOURS  WITH  A THREE-INCH  TELESCOPE. 


Night  Five. 

To  the  east  of  Bootes  lie  the  constellations  Corona 
Borealis  and  Serpens,  which  we  will  to-night  proceed  to 
examine.  Beginning  with  the  former  (which  really  does 
present  more  than  the  ordinary  resemblance  to  the  object 
whose  name  it  bears),  we  shall  find  a very  interesting  double 
star  in  £ (Map  VI.  of  ‘The  Stars  in  their  Seasons’),  the 
components  exhibiting  well- contrasted  colours.  Its  aspect, 
as  seen  with  a power  of  160,  is  shown  in  fig.  64.  a Coronae 
is  a very  pretty  pair.  It  is  delineated  in  fig.  65,  as  viewed 
with  the  same  power  as  the  last  star,  cr  will  be  found  in 
the  sky,  as  nearly  as  may  be,  io°  N.E.  of  a Coronae.  This 
ts  sometimes  ranked  as  a triple  star,  as  the  pair  shown  in 
the  subjoined  sketch  are  followed,  at  a distance  of  51  or 
52",  by  a minute  blue  star.  0-  itself  is  one  of  what  are 
iknown  as  binary  stars,  i.e.  physically  connected  pairs  ; and, 
in  the  description  of  their  orbits  about  their  common  centre 
jof  gravity,  its  components  have  separated  from  i"-3  in  1830, 
to  something  like  3" ‘5  now. 


Fig.  64.  Fig.  65. — <r  Coronas  Bor.  Fig.  66. — 5 Serpentis. 

£ Corona;  Borealis. 


Cne  of  the  most  interesting  of  these  binary  systems,  that 
of  77  Coronae,  is,  unfortunately,  quite  hopelessly  beyond  the 
power  of  our  instrument,  as  the  two  stars  are  now  less  than 
o"7  apart.  Their  distance  varies  from  about  i ''-4  to  o -3, 
and  their  orbit  is  described  in  something  over  forty  years. 
There  are  several  pairs  of  telescopic  stars  in  this  cons' e'la- 
tion,  all  of  them  tolerably  easy  to  divide,  but  it  is  very 


THE  FIXED  STARS  AND  NEBULAE. 


103 


difficult  to  give  directions  for  finding  them,  in  the  absence 
of  an  equatorially  mounted  telescope  with  divided  circles. 
An  easy  one  (Struve  1964)  will  be  found  a little  to  the 
south-west  of  £,  described  above.  While  going  over  Corona 
the  student  should  not  omit  to  glance  at  that  most  aston^ 
ishing  object,  T Coronas,  the  star  which  blazed  up  suddenly 
as  a second  magnitude  one  in  the  year  1866.  Examined 
by  our  greatest  English  spectroscopist,  Dr.  Huggins,  on 
May  16  in  that  year,  it  was  found  to  exhibit  a double  spec- 
trum ; one  analogous  to  that  shown  by  our  own  sun,  the 
other  one  that  of  glowing  gaseous  hydrogen,  thus  (possibly) 
indicating  a conflagration  on  a stupendous  scale.  Subse- 
quently to  this  the  star  faded  to  the  9th  magnitude,  revived 
again  somewhat,  and  has  since  been  irregularly  variable. 
At  present  it  appears  as  a star  of  about  the  9(th  magnitude. 
It  is  situated  on  an  imaginary  line  drawn  from  e Coronse  to 
7r  Serpentis,  at  rather  less  than  one-third  of  the  distance 
between  the  two  from  e. 

Serpens,  to  which  we  shall  next  devote  our  attention 
(‘The  Stars  in  their  Seasons,’  Map  ATI.),  is  one  of  those 
straggling  and  sprawling  constellations  so  difficult  to  follow 
in  the  sky.  Nevertheless,  it  is  one  containing  many  beau- 
tiful and  interesting  objects.  To  begin  with,  a is  a very  wide 
and  unequal  pair,  the  smaller  component  requiring  a good 
deal  of  looking  for  with  a small  telescope.  I mention  it 
here  for  the  pretty  contrast  in  colours  which  it  presents. 
8 Serpentis,  shown  in  fig.  66,  is  a very  neat  and  pretty 
binary  star  ; the  components  are  at  present  separating.  /3  is, 
like  a,  a widish  and  very  unequal  pair,  the  small  star,  as  in 
the  former  case,  being  bluish.  6 Serpentis  is  comparatively 
wide  and  easy.  It  will  well  repay  examination,  though, 
from  the  richness  of  the  region  in  which  it  lies,  y Serpentis, 
4°  north-east  of  77,  is  also  wide  and  easy.  As  before,  I 
mention  it  for  the  pleasingly  contrasted  colours  of  its  com- 
ponents. 5 Serpentis,  90  south-west  of  a,  is  much  closer, 
and  very  unequal ; it  will  repay  examination.  io^°  to  the 
north-east  of  a Serpentis,  on  a line  drawn  from  that  star  to 


io4  HOURS  WITH  A THREE-INCH  TELESCOPE. 


Vega,  will  be  found  49  Serpentis — a fine  pair  shown  in  fig 
67.  This  is  a binary  system,  with  a supposed  period  of  900 
years  ! 59  (or  d)  Serpentis  is  a beautiful  object,  the  colours 

of  its  close  and  unequal  components  being  strongly  con- 
trasted. It  is  represented  in  fig.  68.  Smyth’s  directions 
for  finding  this  star  are,  perhaps,  as  good  as  any.  ‘ To 
identify  59  Serpentis,’  he  says,  * let  an  east-south-east  ray 
be  shot  from  fi  Hcrculis  through  a,  which  will  be  found 
two-fifths  of  the  way  ’ (i.e.  from  /3  Herculis  to  59  Serpentis). 


Fig.  67. — 49  Serpentis.  Fig.  68. — 59  Serpentis.  Fig.  69. — 13  M.  Herculis. 


Libra  (‘The  Stars  in  their  Seasons,’  Map  VI.),  is  neither 
a striking  constellation  to  the  naked  eye,  nor  does  it  con- 
tain many  objects  accessible  to  the  class  of  instrument  we 
are  employing.  A small  but  easy  pair  of  stars  will  be  found 
in  No.  62  of  Piazzi’s  fourteenth  hour.  It  lies  150  east  by  north 
of  Spica  Virginis,  or  2b0  south-west  of  1 in  the  same  constel- 
lation. 90  due  west  of  /?  Scorpii  will  be  found  P.  xv.  91,  a 
not  very  close  but  considerably  unequal  pair.  1 Librae  is  a 
very  wide  and  unequal  pair,  but  worth  looking  at  for  its  pret- 
tily contrasted  colours.  Just  to  the  north-west  of  5 Serpentis, 
of  which  I have  previously  spoken,  will  be  found  that  fine 
compressed  cluster  of  very’  small  stars,  No.  5 of  Messier’s 
catalogue.  It  is  scarcely  resolvable  in  a three-inch  achro- 
matic, and  merely  appears  like  a nebula,  brightening  conspi- 
cuously towards  the  centre. 

We  now  arrive  at  that  somewhat  unintelligible  constella- 
tion, Hercules,  who  appears  head  downwards  in  the  maps 
and  globes,  between  the  constellations  of  the  Northern 
Crown  and  the  Lyre  (‘  The  Stars  in  dreir  Seasons,’  Map  VII.). 


THE  FIXED  STARS  AND  NEBUL.E. 


105 


As  my  present  object,  however,  is  less  to  reconcile  the  configu- 
ration of  the  stars  composing  this  constellation  with  the 
counterfeit  presentment  of  an  inverted  hero,  than  to  select 
from  them  curious  and  beautiful  objects,  suitable  to  the  in- 
strument we  are  employing,  the  map  we  use  will  supply  all 
the  aid  necessary  for  this  purpose.  I say  all  the  aid  ; but 
in  truth  the  map  which  should  give  the  position  of  a quarter 
of  the  interesting  objects  with  which  this  constellation  teems, 
would  have  to  be  a very  elaborate  and  crowded  one  indeed. 
I must  then,  perforce,  confine  myself  to  a few  of  the  most 
easily  identifiable.  Beginning  upon  the  confines  of  Corona 
Borealis,  half-way  between  y and  £ Coronse,  we  shall  find  23 
Herculis.  This  is  a wide  pair,  but  I insert  it  here  for  the 
marked  colour  of  the  smaller  star,  which  will  be  seen  below 
and  just  to  the  right  of  its  primary.  £ Herculis,  a remarkable 
binary  star,  is  quite  beyond  the  power  of  our  telescope — in 
fact,  appears  single  with  the  means  at  our  disposal.  If,  though 
we  fish  along  a line  connecting  77  and  £ Herculis,  about  one- 
third  of  the  way  from  rj  we  shall  light  upon  an  object  which 
will  amply  repay  us  for  any  disappointment  we  may  experi 
ence  in  connection  with  this.  The  object  to  which  I refer 
is  No.  13  of  Messier’s  catalogue,  and  consists  of  a most 
glorious  globular  cluster  of  stars.  How  tar  we  shall  succeed 
in  detecting  its  stellar  character  will  depend  upon  the  excel- 
lence of  our  instrument,  and  the  acuteness  and  training  of 
our  vision.  I have  tried  to  indicate  its  character  in  fig.  69 
above  i^°  north  by  east  of  rj  Herculis  will  be  found  another 
cluster  (Messier  92),  which  the  average  eye  and  instrument 
will  only  show  as  a bright  nebula.  I may  further  note  here 
that  there  are  two  planetary  nebulae  in  this  constellation  ; but 
that  only  one  of  these  is  at  all  within  the  reach  of  a three- 
inch  telescope,  and  neither  can  be  found  with  certainty  save 
in  one  equatorially  mounted. 

Night  Six. 

And  now  we  come  to  the  lovely  object  of  which  fig.  70 
is  nothing  but  a diagram,  a Herculis  ; the  contrast  between 


io5  HOURS  WITH  A THREE-INCH  TELESCOPE. 


the  pronounced  orange  hue  of  the  large  star  and  the  emerald 
green  of  the  smaller  one  being  perfectly  charming.  6 Herculis 
is  a somewhat  wide  and  unequal  pair.  I insert  it  here  on 
account  of  the  extraordinary  discrepancies  which  appear  in 
the  descriptions  of  the  colour  of  its  companion  by  various 
observers  at  different  dates.  This  is  a star  which  the  ob- 
server will  do  well  to  watch,  p Herculis  is  a close  and 
beautiful  double,  the  colour  of  the  companion  being  very  fine. 
It  is  shown  in  fig.  71.  A.  Herculis,  between  S and  p (‘  The 
Stars  in  their  Seasons,’  Map  VII.),  is  only  a single  star,  with 
nothing  but  its  deep  yellow  colour  to  render  it  remarkable  : 
it  is  inserted  here,  though,  since  it  may  interest  the  student 
to  look  at,  or  very  near,  the  point  in  the  heavens  towards 


Fig.  70. — a Herculis.  Fig.  71. — p Herculis.  Fig.  72. — 95  Herculis. 


which  our  entire  solar  system  is  moving  at  the  rate  of  some 
422,000  miles  per  diem. 

One-third  of  the  way  from  a Herculis  towards  Vega  (the 
brilliant  star  in  Lyra)  will  be  found  a widish  pair,  200  of 
Piazzi's  seventeenth  hour  of  R.A.  It  is  noticeable  for  the 
beautifully  contrasted  colours  of  its  unequal  components.  If 
we  draw  an  imaginary  line  from  a Ophiuchi  to  /?  Lyras 
(‘The  Stars  in  their  Seasons,’ Map  VII.),  and  travel  10° 
along  it,  we  shall  arrive  at  95  Herculis,  a tolerably  close  star 
whose  components  differ  but  little  in  magnitude,  although 
they  have  been  alleged  to  do  so  notably  in  colour.  Smyth 
calls  them  ‘apple  green  ’ and  ‘cherry  red.’  Another  ob- 
server describes  them  as  both  golden  yellow.  At  present 
they  appear  to  me  of  a palish  yellow,  both  nearly  of  the  same 
hue.  95  is  represented  in  fig.  72.  p Herculis,  a wide  and 


' THE  FIXED  STARS  AND  NEBUL/E. 


107 


very  unequal  pair,  presents,  as  do  so  many  other  stars  in  this 
constellation,  very  finely  contrasted  colours.  ii°  from  f3 
Lyras,  on  a line  joining  this  star  with  a Herculis,  lies  100 
Herculis,  a pretty  and  easy  little  pair  of  equal  magnitude. 
It  is  shown  in  fig.  73. 

Such  are  a few  typical  objects  among  those  with  which 
this  fine  constellation  abounds.  Purely  telescopic  pairs 
fairly  swarm  in  it,  and  may  be  picked  up  everywhere  by 
simply  sweeping  the  sky.  At  least  seven  well-determined 
variable  stars,  too,  are  numbered  among  its  constituents  ; 
and,  in  addition  to  the  two  clusters  of  stars  of  which  I have 
given  a short  description  above,  it  contains  two  planetary 
nebulae,  and  many  interesting  fields  of  stars.  It  will  prove 
a very  treasure-house  to  the  incipient  observer. 


Fig.  73.  — 100  Herculis.  Fig.  74 .— n Libra;.  Fig.  75.— A Ophiuchi. 


Libra,  situated  beneath  a part  of  Serpens  (‘  The  Stars 
in  their  Seasons,’  Map  VI.),  need  not  detain  us  long.  Its 
two  principal  stars,  a2  and  /?,  have  very  distant  comites,  but 
can  scarcely  legitimately  be  called  ‘ double.’  About  5^° 
to  the  south  by  east  of  a the  observer  will  find  212  of 
Piazzi’s  hour  xiv.  It  is  just  visible  to  the  naked  eye.  It 
forms  a pretty  but  very  easy  pair  with  a moderate  power.  It 
is  really  a triple  star,  but  the  third  component  is  hopelessly 
beyond  our  aperture,  /x  Librte  is  an  extremely  close  pair,  but 
is  said  to  have  been  seen  by  Burnham  with  a 2f,-inch  achro- 
matic. Its  appearance,  as  exhibited  in  an  English  three-inch 
telescope,  is  shown  in  fig.  74.  It  is  not  marked  in  the  map 
to  which  I have  just  referred,  but  will  be  found  a little  more 
than  20  to  the  north  and  west  of  a.  About  6°  west-south- 


lo8  HOURS  WITH  A THREE-INCH  TELESCOTE. 


west  of  n Serpentis  will  be  found  Struve  1962  Librae  a 
pretty  and  delicate,  but  not  difficult  object.  The  remaining 
double  stars  (of  which  there  arc  a good  many)  in  this  con- 
stellation are  all  invisible  to  the  naked  eye.  Before  quitting 
it  we  must  look  at  that  beautiful  object,  5 of  Messier’s  cata- 
logue— a fine  clusur  of  stars  crowded  into  a nebulous-look- 
ing object.  This  lies  nearly  90  to  the  south-west  of  a Serpen- 
tis, and  forms  a rudely  equilateral  triangle  with  that  star  and 
/x  in  the  same  collection. 

Below  Herculis,  and  straggling  in  and  out  of  Serpens, 
Libra,  Scorpio,  and  Sagittarius,  we  find  Ophiuchus,  or  the 
Serpent-bearer.  The  Serpent  borne  by  this  gentleman  I have 
already  described  in  pp.  103  and  104.  I now  turn  to  its  carrier 
himself.  Unlike  Hercules,  the  major  part  of  Ophiuchus 
appears  meagre  and  barren  to  the  naked  eye.  It,  however, 
resembles  that  constellation  in  being  replete  with  objects  of 
telescopic  interest.  Beginning  with  p1 — which  is,  by  the  way, 
terribly  low  down — we  find  a beautiful  close  pair  of  stars,  with 
a pretty  contrast  between  the  pale  yellow  of  the  larger  one 
and  the  blue  of  its  companion  ; the  pair  forming  the  apex 
of  a triangle  with  two  other  companion  stars.  A.  will  tax 
the  observer’s  powers  and  those  of  his  instrument  to  the  very 
utmost.  This  is  a binary  star  with  a period  of  234  years  ; 
its  components  are  very  slightly  opening  just  now.  Fig.  75 
gives  some  idea  of  it  as  seen  as  a merely  oval  object,  with  a 
high  power  under  the  finest  definition.  Some  30  north-west 
of  77  a new  star  blazed  out  in  1848,  subsequently  fading  to  prac- 
tical invisibility  in  small  instruments.  This  neighbourhood 
should  be  watched.  io°  due  east  of  Antares  will  be  found 
36  Ophiuchi,  a pretty  and  fairly  easy  pair.  It  is  too  close 
to  the  horizon,  though,  for  fine  definition  in  these  latitudes. 
39  will  be  found  i°  north-west  of  0 Ophiuchi.  It  is  very 
nearly  as  badly  situated  as  the  last  star.  The  components 
are  not  very  close,  but  their  colours  are  fine.  Another 
star,  much  better  placed,  which  may  be  looked  at  for  the 
colours  of  its  components,  is  67,  4^°  east-south-east  of  /? 
Ophiuchi.  It  is  very  wide,  though,  r,  a most  interesting 


THE  FIXED  STARS  AND  NEBULHL. 


109 


binary  object,  will,  like  A,  prove  a crucial  test  for  the  observer. 
It  will  need  an  instrument  of  the  highest  class,  a high  power, 
a very  sharp  eye  and  an  excellent  night  to  do  anything 
with  it  ; and  even  with  these  advantages  it  will  only  appear 
like  A,  as  a misshapen  star. 

70  Ophiuchi,  6°  to  the  east-south-east  of  /?,  is  an  interest- 
ing pair,  shown  in  fig.  76.  The  colour  of  the  smaller  star  is 
believed,  with  some  reason,  to  be  variable. 

It  used  to  be  violet  or  purple,  and  is  now 
yellowish.  Ophiuchus  is  remarkably  rich 
in  nebulous-looking  star-clusters.  As  they 
are  not  marked  in  our  map,  the  directions 
for  finding  them  will,  I fear,  appear  some- 
what vague.  Beginning  with  12  Messier, 
we  shall  find  this  about  8°  15'  north-west 
by  west  of  e.  10  Messier  is  nearly  half-  76.  . 

J _ J 70  OpniuJii. 

way  between  f3  Librse  and  a Aquilse.  19 
Messier  lies  7^°  due  east  from  Antares.  9 Messier  will 
be  found  30  south-east  of  y Ophiuchi.  About  6^°  to  the  south' 
by  west  of  y lies  14  Messier ; while,  finally,  23  Messier 
Ophiuchi,  a fine  cluster,  will  be  found  about  50  north-west  of 
yu,  Sagittarii. 

Night  Seven. 

The  chief  object  in  the  constellation  Scorpio,  with  which 
I shall  begin  to-night,  a,  or  Antares  (‘The  Stars  in  their 
Seasons,’  Map  VII.),  is  a double  star,  but,  save  under  the 
most  exceptional  atmospheric  circumstances,  beyond  the 
power  of  a three-inch  object-glass.  Nevertheless,  on  a 
superlatively  fine  evening,  and  with  the  highest  power  at  his 
disposal,  the  student  may  pick  up  the  companion  as  a minute  - 
green  speck,  or  wen,  attached  horizontally  to  the  left  of  the 
blazing  red  disc  of  Antares  itself,  v Scorpii  will  be  seen  at 
first  sight  as  a wide  double  star,  but  a little  attention  will 
show  that  the  smaller  star  is  not  single.  (3  Scorpii  is  a 
pretty  and  easy  pair,  the  contrast  of  colouring  in  its  compo- 
nents being  very  pleasing.  It  is  represented  in  fig  77. 


no  HOURS  WITH  A THREE-INCH  TELESCOPE. 


Half-way  between  this  and  Antares,  the  cluster  80  Messier 
may  be  picked  up.  In  the  instrument  we  are  employing, 
however,  it  will  be  seen  as  a nebulous  object,  strongly  re- 
sembling a telescopic  comet,  o-  is  a pretty  pair,  but  terribly 
near  the  horizon.  If  the  student  will  draw  a line  from 
Antares  to  -q  Ophiuchi,  and  travel  io°  along  it  from  a Scorpii, 
he  will  come  upon  236  of  Piazzi’s  hour  xvi.,  a pretty  little 
pair,  which  will  repay  scrutiny.  Closely  following  36 
Ophiuchi  lies  3 1 Scorpii  (this  ought  really  to  be  38  Ophiuchi) 
— a pretty  severe  test  for  a three-inch  telescope  at  any  time, 
and,  at  present,  beyond  its  power. 

Adjoining  Scorpio  to  the  east  is  Sagittarius,  but  this  need 
not  detain  us  long,  as  only  two  suitable  objects  are  to  be 


Fig.  77. — /3  Scorpii.  Fig.  78. — it'  Sagittarii.  Fig.  79. — - Aquilae. 


found  in  the  map  which  we  are  employing.  These  are  /P,  a 
striking  triple  star  represented  in  fig.  78  ; and  22  Messier,  a 
pale  nebulous  mass  half-way  between  [x  and  o-  Sagittarii. 
This  (like  80  M.  described  above)  is  really  a cluster,  but  is 
irresolvable  with  means  at  our  disposal. 

Aquila,  to  the  north  of  Sagittarius,  is  the  next  constella- 
tion we  shall  examine.  Forming  an  equilateral  triangle 
with  c and  £ Aquila  is  n,  a severe  test  for  the  instrument 
we  are  employing.  The  minute  companion,  19"  above  and 
to  the  left  of  the  larger  star,  will  require  the  highest  power 
at  the  observer’s  disposal  to  see  it  at  all.  At  the  right  hand 
extremity  of  the  base  of  an  isosceles  triangle,  whereof 
v Aquilae  forms  the  other  end  and  S Aquilae  the  apex,  23 
Aquilae  will  be  found.  The  comes  of  this  is  also  a star  that 


THE  FIXED  STARS  AND  NEBULAS. 


IT* 


is  invisible  with  any  power  less  than  250  or  so.  ir  Aquiiae 
is  a very  good  test  indeed.  Fig.  79  shows  it  as  seen  at 
moments  of  the  best  definition. 

In  that  pretty  little  constellation,  Delphinus,  the  only  star 
which  need  detain  us  is  y,  depicted  in  fig.  80.  The  con- 
trasted colours . of  the  components  will  at  once  strike  the 
observer’s  eye. 

And  next,  Lyra  will  claim  our  attention  ; and,  as  is  only 
natural,  we  shall  begin  by  directing  our  telescope  to  its 
brilliant  leader,  Vega.  Here,  again,  is  a severe  test,  a fine 
night  and  a pretty  high  power  being  needed  to  glimpse  the 
comes  at  all.  In  fig.  81  I give  something  of  the  appearance 
of  this  object,  but  it  is  impossible  to  reproduce  in  black  and 


Fig.  80. — y Delphini  Fig.  81. — Vega. 


white  the  vivid  blue  blazes  and  the  mouldings  and  twirlings 
of  the  diffraction  rings  which  surround  the  great  star.  More- 
over, the  size  of  the  minute  companion  is  exaggerated,  or  it 
could  not  print  at  all.  Not  far  off  we  shall  find  another 
most  interesting  object.  I refer  to  the  double-double  system 
and  e2  Lyrae,  shown  in  fig.  82.  Between  the  two  pairs 
lies  another  minute  star,  shown  in  my  sketch.  There  are 
two  others  smaller  still  ; they,  however,  require  a larger  aper- 
ture than  ours  to  see  them  at  all.  £ Lyrae  is  a wider  pair, 
but  pretty  from  the  contrasted  colours  of  its  components. 
Between  /?  and  y Lyras,  but  nearer  to  the  former  star,  will 
be  found  that  astonishing  object,  57  Messier  Lyrae,  the 
so-called  4 Ring  Nebula.’  Fig.  83  is  an  attempt  to  give 
some  idea  of  its  aspect  as  seen  with  a power  of  70,  but 


1 12  HOURS  WITH  A THREE-INCH  TELESCOPE. 


wood  engraving  does  not  lend  itself  well  to  the  delineation 
of  nebulae.  1/  Lyrae  is  a widish  double,  but  interesting  from 
the  contrasted  colours  of  its  components. 


Fig.  82. — e1  and  e2  Lyrse.  Fig.  83. — 57  M.  Lyra.  Fig.  84. — /3  Cygni. 


We  will  now  turn  to  that  glorious  region  occupied  by 
Cygnus,  in  which  tne  merest  vague  sweeping  cannot  fail  to 
reveal  innumerable  objects  of  beauty  and  interest.  I shall, 
though,  select  a few  of  the  most  striking  ones  in  it  for 
detailed  description,  as  the  student  can  easily  wander  over 
the  constellation  when  he  has  examined  them.  I will  begin, 
then,  with  /? , the  lovely  colours  of  whose  components  have 
always  rendered  it  a favourite  with  the  juvenile  observer. 
Fig.  84  gives  an  idea  of  the  general  aspect  of  this  star.  1 
north  of  x lies  another  wide,  but  beautifully  coloured  pair, 
278  of  Piazzi’s  hour  xix.  Nor  is  x itself  less  beauti- 
ful and  interesting,  contrasted  colours  again  forming  its 
chief  charm.  1 j/  Cygni,  a close  and  unequal  pair,  will  re- 
quire a high  power  to  see  it.  2°  south  -west  of  e is  49  Cygni, 
shown  in  fig.  85  ; while  30  south  of  c lies  52,  in  which  the  com- 
ponents are  a little  more  widely  separated.  In  both  cases, 
as  is  common  in  this  constellation,  the  diversity  of  colours 
is  very  beautiful.  If  we  draw  an  imaginary  line  from  a 
through  v Cygni,  we  shall  come  upon  a star  (marked,  but 
not  numbered,  in  ‘The  Stars  in  their  Seasons,’  Map  IX.) 
which  must  always  possess  the  highest  interest  for  all  astro- 
nomical students.  This  is  61  Cygni,  the  very  first  of  those 
suns  which  fill  the  universe  whose  distance  from  the  earth 
was  determined  by  the  illustrious  Bessel.  I need  occupy 


THE  FIXED  STARS  AND  NEBULAE. 


H3 


no  further  space,  in  a purely  practical  chapter  like  this,  than  to 
say  that,  so  stupendous  is  the  interval  separating  our  solar 
system  from  this  object  that  light  (travelling  186,326  miles 


Fig.  85.-49  Cygni.  Fig.  86.— 61  Cygni.  Fig.  87.-27  M.  Vulpeculse. 


a second)  takes  something  like  six  years  to  pass  across  it ; so 
that  the  student  whom  my  description  may  tempt  to  look 
at  this  interesting  object  will  see  it  (not  as  it  is  to-night,  but) 
as  it  was  six  years  ago,  when  the  light  which  enters  his  tele- 
scope left  it  ! 61  Cygni  is  shown  in  fig.  86.  Cygnus  is  so 

crowded  with  beautiful  fields  of  stars  as  to  rentier  any  selec- 
tion of  them  for  description  difficult  ; but  the  beginner  may 
hunt  up  M.  39  (roughly,  half-way  between  a and  co  Cygni) 
to  commence  with,  /x  Cygni  is  a very  pretty  triple,  the 
colour  of  the  close  pair  presenting  a pleasing  contrast. 

If  the  reader  will  fish  with  a power  of  70  or  80  between 
/3  Cygni  and  Delphinus,  some  70  south-east  of  the  former 
star  he  will  strike  upon  that  very  curious  object,  27  Messier 
Vulpeculae — the  so-called  ‘ Dumb-bell  ’ nebula,  of  which 
ridiculous  pictures  appear  in  certain  works  on  popular 
astronomy.  I have  done  what  I can  to  present  a portrait 
of  this  nebula  in  fig.  87. 

Night  Eight. 

Capricornus  is  the  next  constellation  which  will  claim 
our  attention.  It  will  not,  however,  detain  us  long  here,  as 
the  objects  in  it  identifiable  upon  Map  IX.  of  ‘ The  Stars 
in  their  Seasons  ’ are  not  numerous.  The  first  of  them  is 


1 


1 14  HOURS  WITH  A THREE-INCH  TELESCOPE. 


that  beautiful  star,  p Capricorni,  represented  in  fig.  88.  The 
contrast  of  colour  is  fine,  o2  is  a pretty  little  pair,  sufficiently 
wide  apart  to  be  resolvable  with  the  lowest  eye-piece.  30 
Messier,  with  a power  of  70  or  so,  will  be  seen  as  a rather 
dim-looking  nebula,  with  an  eighth  magnitude  star  just  pre- 
ceding it  (i.e.,  with  an  inverting  eye-piece,  to  the  left  of  it) 
It  may  be  fished  for  to  the  left  and  below  £ Capricorni, 
just  above  a line  joining  £ with  Fomalhaut,  and  (roughly)  at 
a sixth  of  the  distance. 

Aquarius,  a large  constellation  extending  from  the  south- 
east corner  of  Aquila  over  the  north  and  to  the  east  of 
Capricornus,  is  replete  with  objects  of  interest  suitable  to 
the  instrument  we  are  employing.  Numerous- others,  too 


Fig.  88. — p Capricorni.  Fig.  89.— 41  Aquarii.  Fig.  90.— £ Aquarii. 


small  for  inclusion  in  the  maps  we  are  supposed  to  be  using, 
may  be  picked  up  by  a systematic  search.  Proceeding,  as 
is  our  wont,  in  the  order  of  Right  Ascension,  the  first  object 
we  arrive  at  is  Herschel  iv.  i,  a very  fine  specimen  of  a 
planetary  nebula.  Somewhat  resembling  Uranus,  but  with- 
out his  sharp  outline,  it  is  rather  less  than  i^°  to  the  west  of 
v Aquarii.  Our  next  object,  as  it  happens,  is  a nebula  too, 
but  of  a totally  different  character.  This  is  2 Messier,  a 
large,  bright,  and  (for  a nebula)  conspicuous  object.  It  is 
about  50  north  and  only  just  to  the  east  of  /?  Aquarii. 
About  40  to  the  east  by  south  of  8 Capricorni  will  be  found 
that  delicate  little  pair,  29  Aquarii,  its  components  lying 
diagonally  across  the  field.  If  we  draw  an  imaginary  line 
from  8 Capricorni  to  Fomalhaut,  at  rather  more  than  one- 


THE  FIXED  SEATS  A HD  NEBULAE  1 1 5 

third  of  the  distance  from  the  former  star  we  shall  come 
upon  even  a prettier  star  still,  41  Aquarii,  shown  in  fig.  89. 
£ Aquarii  is  another  beautiful  object,  closer  than  either  of 
the  last  described,  but  perfectly  easy  with  three  inches  o 
aperture  and  a power  of  160.  It  is  shown  in  fig.  90.  r1 
(just  below  and  to  the  right  of  t2  in  Map  X.  of  ‘ The  Stars 
in  their  Seasons  ’)  is  wide,  but  very  difficult,  from  the  small- 
ness of  its  companion,  which  will  be  glimpsed  to  the  right 
and  a little  above  the  larger  star,  i/d  is  another  wide  pair, 
but  interesting  from  the  colours  of  its  components,  which 
are  orange  and  blue.  It  will  be  found  over  the  letter  A in 
the  middle  of  the  word  ‘ Aquarius  ’ in  the  map.  Below  the 
three  stars  lettered  1/9  and  at  the  right  angle  of  a rudely 


right-angled  triangle  which  it  forms  wiih  them  and  8,  lies 
94  Aquarii,  with  its  gracefully  contrasted  colours.  Lastly, 
reference  to  the  map  will  show  a little  group  of  stars  to  the 
right  of  2 Ceti.  The  left  hand  of  the  three  contiguous  ones 
is  107  Aquarii,  which  is  represented  in  fig.  91.  Here,  again, 
varied  colours  come  in  as  an  adjunct  to,  or  element  in,  the 
beauty  of  the  object. 

Over  the  western  part  of  Aquarius  we  shall  find  Equuleus 
in  the  map.  The  second  star  to  the  right  of  the  one  marked 
1 there  is  No.  376  of  Piazzi’s  hour  xx.,  which  I have 
represented  in  fig.  93,  and  which  will  well  repay  examination. 
Here,  again,  in  this  pretty  close  pair  we  have  to  note  beauti- 
fully contrasted  colours,  e Equulei  (the  star  marked  1 in 
the  map),  which  we  shall  see  as  a double  star,  is  really  a 


1 16  HOURS  WITH  A THREE-INCH  TELESCOPE. 


triple  system  ; but  the  extreme  closeness  of  the  companion 
of  the  larger  star  places  it  hopelessly  beyond  the  reach  of 
our  aperture.  A.  Equulei,  represented  in  fig.  93,  is  a charm- 
ing and  delicate  pair,  but  quite  easy  to  divide  with  our  in- 
strumental means.  Both  components  are  white. 


Fig-  93- — A Equulei.  Fig.  94.-51  Piscium.  Fig.  95.-65  Piscium. 


Adjoining  Equuleus  to  the  east  is  the  large  constellation 
Pegasus.  1 Pegasi,  bordering  on  Vulpecula,  is  a very  wide 
pair.  It  is  inserted  here  for  the  finely  contrasted  colours 
of  its  components.  If  we  join  e Pegasi  and  S Equulei  by 
an  imaginary  line,  and  consider  this  as  the  base  of  a very 
squat  triangle  having  its  apex  to  the  north,  then  at  this 
apex  will  be  found  15  Messier  Pegasi,  a fine  object,  pre- 
senting the  appearance  of  a bright  nebula,  with  marked 
central  condensation.  It  is  really  a brilliant  cluster  of  stars, 
but  a three-inch  telescope  is  quite  impotent  to  resolve  it. 
€ Pegasi  is  a very  wide  triple,  but  the  colours  render  it 
interesting,  k Pegasi  will  tax  both  the  eye  and  the  in- 
strument of  the  student  severely.  In  fact,  to  see  the 
minute  comes  at  all  he  must  remain  in  the  dark  for  some 
little  time,  and  even  then  he  will  only  glimpse  it  ‘ out  of 
the  corner  of  his  eye.’  It  is  some  12"  from  its  primary, 
below  and  to  the  left  of  it.  I cannot  give  a diagram  of 
it  to  scale,  inasmuch  as  the  minute  star  would  not  print  at 
all. 

Bounded  by  Pegasus,  Aquarius,  Cetus,  Aries,  and 
Andromeda,  is  the  straggling  and  not  very  intelligible 
constellation  Pisces.  If  we  draw  an  imaginary  line  from 


THE  FIXED  STARS  AND  NEBULsE.  117 

y Pegasi  to  rj  Ceti,  about  one-third  of  the  way  from  the 
first-named  star  we  shall  come  upon  51  Piscium,  a wide  but 
very  pretty  pair,  represented  in  fig.  94.  Note  the  lilac  tint 
of  the  small  companion.  55  Piscium,  our  next  object,  will 
be  found  some  70  along  a line  through  S and  e Andromedae. 
The  components  of  this  charming  object  are  very  much 
closer  than  those  of  the  previous  one,  being,  in  fact,  some- 
thing like  one-fifth  of  the  distance.  The  comes,  though 
minute,  will  be  detected  without  difficulty.  About  half- 
way between  tt  and  rj  Andromedae  we  come  upon  65 
Piscium,  a fine  and  rather  close  pair  of  very  nearly  equal 
stars.  This  is  shown  in  fig.  95.  Piscium,  the  small  un- 
named star  to  the  south-east  of  77  Andromedae  on  the  map 
is  another  equal  pair,  but  very  considerably  wider  apart,  and 
easily  separable  with  the  lowest  eye -piece.  £ is  also  a very 
wide  and  easy  star,  but  in  this  case  the  components  are  un- 
equal. The  last  object  identifiable  from  the  map  we  are  using 
is  the  leading  star  in  the  constellation,  a.  This  fine  pair  is 
represented  in  fig.  96. 


Fig.  96. — a Piscium.  Fig.  97. — 1 Trianguli. 


Before  quitting  this  region  of  the  sky  we  will  just 
direct  our  instrument  to  that  lovely  little  pair,  i Trianguli, 
which  we  inadvertently  omitted  while  describing  the  constel- 
lation Aries  on  pp.  87  and  88.  It  is  not  lettered  in  the  map  to 
which  I have  so  often  referred,  but  is  the  star  over  the  letter 
U in  ‘ Triangula.’  Its  aspect  is  shown  in  fig.  97.  Its  finely 
contrasted  colours  are  unfortunately  incapable  of  reproduc- 
tion on  a wood  block. 


1 1 8 HOURS  WITH  A I HREE-1H  CH  TELESCOPE, 


Night  Nine. 

Our  final  night  I propose  to  devote  to  the  circumpolar 
constellations,  or  those  which  wholly  or  in  part  remain 
always  above  our  horizon  in  these  latitudes.  First,  then,  let 
us  turn  to,  perhaps,  the  best  known  of  them  all — Ursa  Major. 
We  will  begin  by  turning  our  telescope,  armed  with  a power 
of  120,  upon  £ (Mizar).  Sharp-sighted  people  will  detect 
with  the  naked  eye  a small  star  (Alcor)  in  the  immediate 
neighbourhood  of  Mizar.  In  the  telescope,  with  the  power 
specified,  Mizar  itself  will  be  seen  to  be  double,  and  form- 
ing with  Alcor  the  pretty  triple  system  shown  in  fig.  98. 

The  pale  green  of  the  small  star  of  the  pair  will  be  noted. 
£ Ursse  Majoris,  examined  with  the  very  highest  power  at 
the  disposal  of  the  observer,  will  furnish  an  absolutely 
crucial  test  of  the  excellence  at  once  of  his  eye  and  tele- 
scope. 23  Ursae  Majoris  is  rather  a wide  pair,  but  interest- 
ing from  the  different  tints  of  its  components.  57  is  a pretty 
pair  for  a similar  reason,  but  very  much  closer  than  the 
last  ; it  is  unnumbered  in  the  map.  65,  a fine  triple,  is 
also  unnumbered,  but  may  be  recognised  to  the  south  of  x 
on  the  boundary  of  Canes  Venatici.  y Ursse  Majoris  lies 
in  a fine  field  of  stars.  This  constellation,  I may  remark, 
swarms  with  double  and  triple  stars,  but,  as  in  a large  pro- 
portion of  cases  they  are  of  less  than  the  sixth  magnitude, 
the  map  takes  no  account  of  them,  and  it  would  be  useless 
to  give  their  co-ordinates  unless  the  observer’s  instrument 
were  equatorially  mounted.  Several  interesting  nebulas  are 
to  be  found  in  Ursa  Major,  but,  in  the  case  of  the  student 
for  whom  these  papers  are  written,  it  can  only  be  by  fishing. 
If  he  will  conceive  an  equilateral  triangle  to  be  described, 
with  a and  23  Ursae  Majoris  at  the  extremities  of  its  base  : 
then,  by  sweeping  about  to  the  right  of  its  apex  with  the 
very  lowest  power  he  possesses,  he  may  hit  upon  the  two 
nebulae  81  and  82  Messier,  apart.  About  2°  (four  dia- 
meters of  the  moon)  south-east  of  /?  is  another  nebula,  97 
Messier,  a pale  circular  object,  looking  like  the  ghost  of  a 


THE  FIXED  STARS  AND  NEBULAS. 


119 


planet.  An  imaginary  line  drawn  diagonally  from  a through 
y Ursae,  and  continued  nearly  as  far  again,  will  strike  upon 
y v.  43,  an  oval  nebula.  Half-way,  too,  between  f3  and 
97  Messier  lies  y v.  46.  This  will  require  some  gazing  at 
with  so  small  an  aperture. 

And  now  we  will  direct  our  telescope,  armed  with  a power 
of  160,  to  the  Pole  Star,  which  will  be  seen  as  depicted  in 
fig.  99. 

This  is  sometimes  alleged  to  be  a test  for  a three-inch 
telescope,  but  it  is  not  so.  Dawes  has  seen  the  companion 
with  a 1 '3-inch  object-glass,  and  the  eagle-eyed  Ward,  of 
Belfast,  with  only  1 '25-inch  aperture  ! North-west  of 
£ Ursae  Minoris  will  be  found  tt1,  a wide  and  easy  object. 


Fig.  98. — f Ursa;  Majoris.  Fig.  99.— The  Pole  Star.  Fig.  100.— 7)  Cassiopeia:. 


Cassiopeia  is  one  of  the  constellations  through  which 
the  Milky  Way  p isses,  and  hence  it  affords  innumerable 
rich  fields  and  clusters  to  repay  the  observer  who  sweeps 
and  fishes  over  it.  y,  to  begin  with,  lies  in  a fine  field  of 
small  stars.  r\  Cassiopeia,  shown  in  fig.  100,  as  viewed 
with  a power  of  160,  is  a beautiful  object,  the  colours  being 
so  well  contrasted,  i/r  is  a triple  star,  but  with  our  optical 
means  will  only  be  seen  as  a rather  wide  double.  <r  Cassio- 
peiae,  to  the  south  of  /?,  is  a beautiful,  delicate,  and  by  no 
means  easy  double  star — a sort  of  miniature  of  e Bootis. 
About  k,  between  y and  k,  lie  some  of  the  beautiful  fields  of 
stars  to  which  reference  has  been  made  above. 

Camelopardus  contains  several  more  or  less  striking 
pairs,  but  as  none  of  them  are  marked  in  our  map  of  refer- 
ence we  pass  on  to  Lynx,  where  we  find  38  (Map  III.  of 


120  HOURS  WITH  A THREE-INCH  TELESCOPE. 


‘ The  Stars  in  their  Seasons  ’),  a very  dose,  delicate,  and 
rather  difficult  pair.  19  Lyncis  is  a pretty  triple,  but  it  does 
not  appear  on  the  map. 

The  sprawling  constellation  Draco,  which  straggles  over 
so  much  of  the  circumpolar  sky,  is  our  next  in  order  for 
examination.  From  its  situation  the  amateur  can  scarcely 
expect  to  scrutinise  many  of  its  chief  objects  in  succession 
without  getting  a backache,  and  a stiff  neck  to  boot,  so 
inconveniently  are  they  placed.  Let  us,  however,  express 
a hope  that  the  intellectual  pleasure  to  be  derived  from 
such  a search  may  quite  outweigh  its  concomitant  physical 
discomfort.  If  we  draw  a line  from  y Draconis,  through 
1 3 , and  carry  it  on  twice  the  distance  between  them,  we 
shall  strike  17  Draconis,  a pretty  and  interesting  triple. 
/j.  Draconis,  a close  but  easy  pair,  is  shown  in  fig.  101. 
Rather  more  than  i^°  south  of  /?  Draconis  is  a small  but 
very  pretty  double  star,  147  of  Piazzi’s  hour  xvii.  It 
is  invisible  to  the  naked  eye.  If  we  draw  a line  from  the 
Pole  Star  to  y Draconis,  and  fish  on  it,  about  half-way 
between  those  stars,  with  a low  power,  we  shall  light  upon 
that  strange  object,  Herschel  37,  iv.  Draconis.  This  is 
the  nebula  which  our  greatest  living  English  spectroscopist, 
Dr.  Huggins,  found  to  be  gaseous,  in  1864.  Viewed  in  the 
instrument  employed  for  the  purpose  of  these  papers,  it 
presents  the  appearance  of  a large  pale  blue  star  out  of 
focus.  South-east  of  e Ursae  Minoris,  40  Draconis  will  be 
found.  It  is  a wide  and  easy  pair.  39  Draconis,  half-way 
between  y and  8,  appears  in  the  books  as  a triple  star.  It 
will  require  an  extremely  fine  night  and  a high  power,  how- 
ever, to  show  the  comes  to  the  principal  star,  whose  light 
and  proximity  quite  overpower  it ; so  that  it  will  ordinarily 
appear  as  a very  wide  double  only,  in  a three-inch  telescope, 
o Draconis  is  a wide  pair,  but  the  colours  are  very  pretty. 
The  last  object  in  this  constellation  which  we  shall  look  at 
to-night,  € Draconis,  will  form  a severe  test,  at  once  for 
the  observer’s  instrument  and  his  eye,  and  for  the  state  of 
the  atmosphere.  He  must  employ  the  highest  power  at 


THE  FIXED  STARS  AND  NEBULAS. 


121 


his  command,  and  even  then  the  companion  will  often  be 
involved  in  the  diffraction  ring  surrounding  the  larger  star. 
Fig.  102  gives  an  idea  of  this  star  when  caught  at  moments 
of  the  best  vision. 


Fig.  ioi. — /a  Draconis.  Fig.  102. — e Draconis. 


An  examination  of  one  more  circumpolar  constellation — 
I mean  Cepheus — will  complete  our  survey  of  the  heavens, 
round  the  whole  twenty-four  hours  of  which  we  have  now 
travelled.  To  begin  with,  the  reader  may  find  a very  severe 
test  for  the  light-grasping  power  of  his  instrument,  and  the 
excellence  of  his  own  eye,  in  191  of  Piazzi’s  hour  ii.,  which 
lies  at  a distance  of  some  io°  on  a line  leading  from  the 
Pole  Star  to  f3  Persei.  The  components  are  close,  and  the 
observer  will  need  a very  dark  night  and  excellent  definition 


Fig.  103.— k Cephei.  Fig.  104.—  f Cephei.  Fig.  105.-0  Cephei. 


to  see  the  companion  at  all.  k Cephei  (shown,  but  not 
lettered,  in  the  map  in  an  odd  little  corner  of  the  constella- 
tion running  into  Draco)  is  a fine  pair,  which  will  be  seen 
as  in  fig.  103.  y8  is  a wider,  and  also  an  unequal  pair. 
In  each  of  these  cases  the  small  star  is  blue.  To  the  east- 


K 


122  HOURS  WITH  A THREE-INCH  TELESCOTE. 


north-east  of  a Cephei  is  a vertical  line  of  small  stars.  The 
upper  one  of  these  is  £,  a tolerably  close  and  somewhat 
unequal  pair,  which  will  "repay  examination.  It  is  repre- 
sented in  fig.  104.  8 Cephei  is  a beautiful  object,  being, 

as  Webb  says,  ‘something  like  (3  Cygni.’  Finally  we  arrive 
at  o Cephei,  a very  close  and  unequal  pair,  delineated  in 
fig.  105.  Both  in  this  and  8 the  small  stars  are  blue,  as 
are,  curiously,  so  many  of  the  comites  in  this  constellation. 

I may  say  in  conclusion  that  in  these  chapters  I have 
simply  endeavoured  to  describe  a few  of  the  chief  and  most 
easily  recognisable  objects  on  the  face  of  the  celestial  vault, 
that  are  well  within  the  optical  power  of  a three-inch  tele- 
scope. Had  I been  justified  in  assuming  that  all  my  readers 
were  in  possession  of  Proctor’s  admirable  1 Star  Atlas,’  I 
might  have  extended  my  list  almost  indefinitely.  Even  as 
it  is,  I may  be  permitted  to  express  a hope  that  I have  not 
wholly  failed  in  my  attempt  to  indicate  what  a mine  of  in- 
struction and  delight  lies  before  the  possessor  of  even  so 
small  an  instrument  as  that  to  which  my  descriptions  have 
had  reference. 

Finally,  in  connection  with  the  stellar  portion  of  the 
subject,  I may  say  here,  that  should  any  possessor  of  athree- 
inch  telescope  desire  to  verify  what  he  may  have  heard  or 
read  with  reference  to  spectrum  analysis,  as  applied  to  these 
distant  suns  we  have  been  examining,  McClean’s  Star  Spec- 
troscope is  the  only  one  at  all  applicable  to  such  an  instru- 
ment as  that  whose  employment  I have  presupposed.  With 
that  exceedingly  ingenious  little  instrument  the  spectra  of 
such  stars  as  Sirius,  Vega,  Aldebaran,  or  a Orionis  may  be 
fairly  well  seen,  even  in  a three-inch  telescope. 


Spottiswoodc  & Co.  Printers,  New- street  Square,  London. 


N753H 


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